Multistep reduction gear

ABSTRACT

The invention relates to a multi-step reduction gear, comprising a drive shaft ( 1 ), which is connected to a front-mounted gear group (VS), an output shaft ( 3 ), which is connected to a rear-mounted gear group (NS), switch elements (A, B, C, D, E) acting on the front-mounted gear group (VS) and switch elements (M, H, L) acting on the rear-mounted gear group (NS). By selectively switching said switch elements (A, B, C, D, E and M, H, L) an input speed (n) of the drive shaft ( 1 ) can be transmitted to the output shaft ( 3 ) for the purpose of shifting at least seven forward gears in such a way that in order to change from one gear to the next highest or next lowest gear the switch elements that have just been actuated only disconnect one switch element and connect one further switch element. Pursuant to the invention it is suggested to design the front-mounted gear group (VS) from two coupled, shiftable front-mounted planetary gear sets (VS 1,  VS 2 ) and a maximum of two further non-shiftable front-mounted planetary gear sets (VSA, VSb), wherein the rear-mounted gear group (NS) is firmly connected to the front-mounted gear group (VS) by means of a spacer shaft ( 2 ) rotating at an output speed (nvs) of the front-mounted gear group (VS) and can be connected to the drive shaft ( 1 ) by means of at least one second switch element (H) acting on the rear-mounted gear group (NS), and wherein the output speed (nvs) of the front-mounted gear group (VS) is generated by selectively closing switch elements (A, B, C, D, E) acting on the front-mounted gear group (VS).

[0001] The present invention relates to a multi-step reduction gearpursuant to the preamble of patent claim 1.

[0002] The older German patent application P 199 49 507.4 by theapplicant describes several gear patterns for an automatic multi-stepreduction gear with various combinations of coupled planetary gear sets.Through the suitable connection of a non-shiftable front-mounted geargroup combination to a shiftable rear-mounted gear group combination atleast seven forward gears can be switched, respectively, without amultiple connection. The number of shiftable forward gears is herebygreater than the number of switch elements by a factor of at least two.

[0003] DE-P 199 49 507.4 suggests the development of the shiftablerear-mounted gear group combination as a two-planet carrier/four-shafttransmission with two shiftable rear-mounted planetary gear sets. Atwo-planet carrier/four-shaft transmission should be interpreted here asan arrangement of two individual mechanically coupled single carrierplanetary gear sets where the coupled unit contains four so-called “freeshafts” due to the double component connection feature, wherein a“shaft” can be a sun wheel, a ring gear or a planet carrier of aplanetary gear set.

[0004] It is now the object of the present invention, proceeding fromthe known state-of-the-art, to develop further a multi-step reductiongear with at least seven forward gears that can be shifted without amultiple connection with comparatively little construction effort,unmodified favorable gear steps and large spread.

[0005] This object is achieved by a multi-step reduction gear exhibitingthe features of the main claim 1 or the dependent claim 23.

[0006] Proceeding on the state-of-the-art from DE-P 199 49 507.4, themulti-step reduction gear comprises a front-mounted gear group that isconnected to the drive shaft and a rear-mounted gear group that isconnected to the output shaft of the transmission.

[0007] In a first solution of the task pursuant to the invention, boththe front-mounted group and the rear-mounted group are each designed ascoupled, shiftable planetary gear sets and are connected with each otherby means of a spacer shaft.

[0008] In a second solution to the task pursuant to the invention, thefront-mounted group is formed by two front-mounted planetary gear setsthat are independent of each other, of which at least one can beshifted, while the rear-mounted group is formed by coupled, shiftableplanetary gear sets. “Independent” here should be interpreted so thateach of the two front-mounted planetary gear sets generates a speed thatis not influenced by an active connection between the two front-mountedplanetary gear sets. The output speed of the front-mounted group here istherefore created either by the first or the second front-mountedplanetary gear set, however, not by both simultaneously.

[0009] The shiftable rear-mounted group can always be connected to thedrive shaft of the transmission by means of at least one switch elementand is always firmly attached to the spacer shaft—i.e., the output ofthe shiftable front-mounted group.

[0010] Pursuant to the invention, by selectively switching the switchelements acting on the shiftable front-mounted group, a certain speed isgenerated on the output of the front-mounted group, at which the spacershaft rotates.

[0011] In each gear that is engaged, at least two switch elements areswitched. When changing from one gear to the next highest, only oneswitch element is disconnected and a further switch element isconnected, thus avoiding multiple connections critical for shiftingquality for which several switch elements would have to be connected ordisconnected simultaneously.

[0012] The dependent claims reveal preferred designs of the invention,in which as many gears as possible can be shifted with the smallestpossible number of switch elements and planetary gear sets, and amulti-step reduction gear can accordingly be produced inexpensively.

[0013] The following described the invention by way of example based onthe designs of a multi-step reduction gear as depicted in the figures.They show,

[0014]FIGS. 1A and 1B a first design of a multi-step reduction gearpursuant to the invention with nine forward gears and one reverse gear;

[0015]FIGS. 2A and 2B a second design of a multi-step reduction gearpursuant to the invention with nine forward gears and one reverse gear;

[0016]FIGS. 3A and 3B a third design of a multi-step reduction gearpursuant to the invention with nine forward gears and one reverse gear;

[0017]FIGS. 4A and 4B a fourth design of a multi-step reduction gearpursuant to the invention with eleven forward gears and one reversegear;

[0018]FIGS. 5A and 5B a fifth design of a multi-step reduction gearpursuant to the invention with eleven forward gears and one reversegear;

[0019]FIGS. 6A and 6B a sixth design of a multi-step reduction gearpursuant to the invention with fifteen forward gears and one reversegear;

[0020]FIGS. 7A and 7B a seventh design of a multi-step reduction gearpursuant to the invention with nine forward gears and one reverse gear;

[0021]FIGS. 7C and 7D a further development of the seventh design of amulti-step reduction gear pursuant to the invention;

[0022]FIGS. 8A and 8B an eighth design of a multi-step reduction gearpursuant to the invention with nine forward gears and one reverse gear;

[0023]FIGS. 9A and 9B a ninth design of a multi-step reduction gearpursuant to the invention with nine forward gears and one reverse gear;

[0024]FIGS. 10A and 10B a tenth design of a multi-step reduction gearpursuant to the invention with eleven forward gears and three reversegears;

[0025]FIGS. 11A and 11B an eleventh design of a multi-step reductiongear pursuant to the invention with eleven forward gears and threereverse gears;

[0026]FIGS. 12A and 12B a twelfth design of a multi-step reduction gearpursuant to the invention with seven forward gears and one reverse gear(pursuant to the second solution of the invention);

[0027]FIGS. 13A and 13B a thirteenth design of a multi-step reductiongear pursuant to the invention with seventeen forward gears, without areverse gear;

[0028]FIGS. 14A and 14B a fourteenth design of a multi-step reductiongear pursuant to the invention with seventeen forward gears, without areverse gear;

[0029]FIGS. 15A and 15B a fifteenth design of a multi-step reductiongear pursuant to the invention with twenty-four forward gears, without areverse gear;

[0030]FIGS. 16A and 16B a sixteenth design of a multi-step reductiongear pursuant to the invention with twenty-six forward gears, without areverse gear;

[0031]FIGS. 17A and 17B a first design of a second rear-mounted grouppursuant to the invention;

[0032]FIGS. 17C and 17D a second design of a second rear-mounted grouppursuant to the invention; and

[0033]FIGS. 17E and 17F a seventeenth design of a multi-step reductiongear pursuant to the invention with thirty-five forward gears, without areverse gear.

[0034] The Figures show, in accordance with the respective design of themulti-step reduction gear, the gear pattern (Figures Index A or C or E)as well as the shift logic with appropriate exemplary gear ratios of theindividual gears, gear steps, gear spreads and gear (Figures Index B orD or F).

[0035] In order to create multi-step reduction gears with at least sevenforward gears that can be produced comparatively inexpensively ascompared to DE-P P 199 49 507.4, the front-mounted gear groupcombination is incorporated in a shiftable manner on the drive shaft ofthe transmission. This configuration generates another speed as afunction of the actuated switch elements, wherein said speed acts on thelikewise shiftable rear-mounted group combination on the output shaft ofthe transmission in addition to the input speed that is introduced bymeans of the drive shaft. In accordance with the actuation logic of theswitch elements, the front-mounted group can optionally also be arrangedin a block or be fixed.

[0036] In the multi-step reduction gear described above, a front-mountedgroup that is connected to the drive shaft creates two additional speedsthat act on the rear-mounted group together with the input speed. Incontrast to the present invention, these two speeds are generated byarranging two non-shiftable front-mounted planetary gear sets.

[0037] By actuating the switch elements in the present invention, theoutput speed of the front-mounted gear group combination and the inputspeed of the transmission are thus transmitted to the output shaft inaccordance with the flow of power. Through the special configuration ofthe switch elements and planetary gear sets, various multi-stepreduction gears, which are described in detail in the following, can bedesigned with at least seven forward gears, especially for passengervehicles, busses and trucks. A multi-gear transmission without a reversegear can be produced for use in motorcycles and bicycles.

[0038] The drive shaft 1 of the transmission and an output shaft 3 ofthe multi-step reduction gear are designated in all Figures. Themulti-step reduction gear always comprises a shiftable front-mountedgroup VS and a shiftable rear-mounted group NS that is connected to theVS via a spacer shaft 2. The drive shaft 1 rotates at an input speed n.When two switch elements of the front-mounted group VS pursuant to theswitch logic of the transmission are shifted, i.e., closed, the spacershaft 2 rotates at an output speed nvs of the front-mounted group VS.The output shaft 3 rotates at an output speed nns of the rear-mountedgroup NS. In the following descriptions, VS1, VS2. VSa and VSb will marka first, second, third, and fourth front-mounted planetary gear group,respectively, which are available depending on the design. Likewise,NS1, NS2, NS3 and NS4 will designate a first, second, third and fourthrear-mounted planetary gear group, respectively, which are availabledepending on the design. Depending on the design, up to five switchelements (clutches or brakes) A, B, C, D, and E acting on thefront-mounted group can be provided, as well as up to five switchelements (clutches or brakes) M, H, L, M′ and H′ acting on therear-mounted group.

[0039] The following describes six multi-step reduction gears pursuantto the invention by way of example with FIGS. 1A and 1B through 6A and6B, which can be shifted by means of four switch elements A, B, C, D(FIGS. 1A, 1B and 3A, 3B) and/or four switch elements A, B, D, E (FIGS.2A, 2B) or five switch elements A, B, C, D, E (FIGS. 4A, 4B through 6A,6B) in the front-mounted group VS and two switch elements M, H in therear-mounted group NS.

[0040] The front-mounted group VS is hereby designed as a shiftabletwo-planet carrier/four-shaft transmission with two coupledfront-mounted planetary gear sets VS1 and VS2, wherein at least one freeshaft of this two-planet carrier/four-shaft transmission can beconnected to the drive shaft 1 by means of one of the switch elements A,B, C, D or E and at least one free shaft of this two-planetcarrier/four-shaft transmission can be fixed by means of one further ofthe switch elements A through E. The speed nvs that isgenerated—depending on the actuated switch elements—on the output of thefront-mounted group VS is rigidly transmitted to the rear-mounted groupNS via the spacer shaft 2. The speed nvs can also be zero, i.e., thefront-mounted group can be blocked against the gear housing. The speednvs can also be equal to the input speed n of the drive shaft 1, i.e.,the front-mounted group VS can also revolve as a block.

[0041] Not coupled in the front-mounted group VS are a spider gear ofthe first front-mounted planetary gear set VS1, wherein said gear isconnected to the first switch element A, a spider gear of the secondfront-mounted planetary gear set VS2, wherein said gear is connected tothe second and third switch elements B and C, as well as a planetcarrier of the second front-mounted planetary gear set VS2 that isconnected to the fourth switch element D and/or fifth switch element Eand the spacer shaft 2 between the front-mounted and rear-mountedgroups. Hereby a spider gear is defined as a sun wheel or a ring gear.

[0042] The shiftable rear-mounted group NS is also a shiftabletwo-planet carrier/four-shaft transmission that comprises the coupledrear-mounted planetary gear groups NS1 and NS2 and the switch elements Mand H. Here, the rear-mounted group NS can be connected to the gearhousing via its first switch element M and to the drive shaft 1 via itssecond switch element H.

[0043] Not coupled in the rear-mounted group NS are a spider gear of thefirst rear-mounted planetary gear set NS1, wherein said gear isconnected to the switch element M designed as a brake, and a spider gearof the second rear-mounted planetary gear set NS2, wherein said gear isconnected to the spacer shaft 2, as well as a shaft of the secondrear-mounted planetary gear set NS2 that is connected to the switchelement H and the output shaft 3. A spider gear can hereby beinterpreted either as a sun wheel or a ring gear of the appropriateplanetary gear group.

[0044] In the first six designs of the multi-step reduction gearpursuant to the invention in accordance with FIGS. 1 through 6, the gearratios are always formed through the front-mounted and rear-mountedgroups will, two switch elements being closed in the front-mounted groupVS, respectively, and one switch element being closed in therear-mounted group NS.

[0045] With regard to the speeds on the shafts and switch elements, thefollowing applies to the first solution of the task pursuant to theinvention and specifically to the first through sixth designs of theinventive multi-step reduction gear pursuant to FIGS. 1 through 6:

[0046] 1. The speed on the drive shaft 1 and on the switch elements Eand H is the same (input speed n);

[0047] 2. the speed on the actuated switch element A is in the rangefrom greater than/equal to zero to smaller than/equal to the input speedn of the drive shaft 1;

[0048] 3. the speed on the actuated switch element D is greaterthan/equal to zero and smaller than the input speed n on the drive shaft1;

[0049] 4. the speed on the spider gear of the second rear-mountedplanetary gear set NS2, wherein said gear is connected to the spacershaft 2, is equal to/greater than one of the speeds nvs generated by thefront-mounted groups VS in the case of actuated switch elements H and M;

[0050] 5. the speed on the shaft, which connects the switch elements Band/or C to a spider gear of the second front-mounted planetary geargroup VS2, is smaller than/equal to the speed generated with an actuatedswitch element B or C in the case of actuated switch elements A and D;

[0051] 6. the speed on the shaft, which connects the switch elements Band/or C to the spider gear of the second front-mounted planetary gearset VS2, is greater than/equal to the speed generated with an actuatedswitch element B or C in the case of actuated switch elements A and E;and

[0052] 7. the speed on the actuated switch element M is equal to zero.

[0053] The mechanical clutches of the front-mounted planetary gear groupcomponents are identical to each other in the first, fourth and sixthdesigns of an inventive multi-step reduction gear, respectively, as arethe mechanical clutches of the rear-mounted planetary gear setcomponents. The second and third designs of an inventive multi-stepreduction gear are derived from the first design, each with a differentclutch within the front-mounted group VS and the rear-mounted group NS.The fifth design of a multi-step reduction gear pursuant to theinvention is derived from the fourth design, with a different clutchwithin the rear-mounted group NS, as well. Needless-to-say, othermechanical clutches of the planetary gear group components are alsofeasible in other further developments.

[0054]FIGS. 1A and 1B show by way of example a first design of aninventive multi-step reduction gear, with nine forward gears and onereverse gear. As depicted in FIG. 1A, this first design of the inventivemulti-step reduction gear comprises two shiftable front-mountedplanetary gear sets VS1 and VS2, which are coupled to a two-planetcarrier/four-shaft transmission, and two shiftable rear-mountedplanetary gear sets NS2 and NS2, which are likewise coupled to atwo-planet carrier/four-shaft transmission.

[0055] The first shiftable front-mounted planetary gear set VS2comprises a sun wheel 11, a planet carrier 15 with planetary gears 12and a ring gear 13. Equivalent to said nomenclature, sun wheels aremarked with 21, 31 and 41, planet carriers are designated 25, 35 and 45comprising planetary gears 22, 32 and 42, and ring gears are marked with23, 33 and 43 for the second front-mounted planetary gear set VS2, thefirst rear-mounted planetary gear group NS1 and the second rear-mountedplanetary gear group NS2, respectively.

[0056] The drive shaft 1 (speed n) can be connected to the sun wheel 11by means of a first clutch A of the front-mounted group VS, to the sunwheel 21 by means of a second clutch B of the front-mounted group VS andto the planet carrier 45 of the planetary gears 42 by means of a secondclutch H of the rear-mounted group NS. The sun wheel 21 can be fixedthrough a third switch element C of the front-mounted group VS, whereinsaid element is designed as a brake. The planet carrier 25 with theplanetary gears 22 is connected to the ring gear 13 and can be fixedthrough a fourth switch element D of the front-mounted group VS, whereinsaid element is designed as a brake. Moreover the ring gear 23 isconnected to the planet carrier 15 of the planetary gears 12 and to thesun wheel 41 through the spacer shaft 2 (speed nvs). The sun wheel 31can be fixed by means of a first switch element M of the rear-mountedgroup NS, wherein said element is designed as a brake. The planetcarrier 45 with the planetary gears 42 is connected to the ring gear 33,and the planet carrier 35 with the planetary gears 32 is connected tothe ring gear 43 and to the output shaft 3 (speed nns).

[0057] By selectively switching the overall six switch elements A, B, C,D, M and H, pursuant to the shift logic shown in FIG. 1B, a total ofnine forward gears and one reverse gear R can be shifted.

[0058] As compared to equivalent gear designs pursuant to theaforementioned state-of-the-art, the multi-step reduction gear pursuantto the invention beneficially comprises a total of three brakes.Especially with regard to the compressed oil supply for actuating theswitch elements, this results in a clearly more simplified design.

[0059]FIGS. 2A and 2B show by way of example a second design of aninventive multi-step reduction gear, with nine forward gears and onereverse gear. In the front-mounted group VS two shiftable, coupledfront-mounted planetary gear sets VS1 and VS2 as well as four switchelements A, B, D and E are provided, in the rear-mounted group NS it istwo shiftable, coupled rear-mounted planetary gear sets NS1 and NS2 aswell as two switch elements M and H.

[0060] The first shiftable front-mounted planetary gear set VS1 herecomprises a sun wheel 11, a planet carrier 15 with planetary gears 12and a ring gear 13. Analogous to the preceding nomenclature, sun wheelsare marked with 21, 31 and 41, planet carriers are designated 25, 35 and45 comprising planetary gears 22, 32 and 42, and ring gears are markedwith 23, 33 and 43 for the second front-mounted planetary gear set VS2,the first rear-mounted planetary gear group NS1 and the secondrear-mounted planetary gear group NS2, respectively.

[0061] Compared to the previously described first design, the brake Cprovided there, which in the switched state always generates a speed ofzero on the free shaft of the two-planet carrier/four-shaft transmissionconnected thereto, has been eliminated. The brake D thus forms the thirdswitch element of the front-mounted group VS. A clutch E, which in theswitched state always generates a speed that is equal to the input speedn of the drive shaft 1 on the free shaft of the two-planetcarrier/four-shaft transmission connected thereto, is here provided asthe fourth switch element.

[0062] As shown in FIG. 2A, the drive shaft 1 (speed n) can be connectedto the sun wheel 21 through a second switch element B of thefront-mounted group VS designed as a clutch and to the planet carrier 45of the planetary gears 42 through a second clutch H of the rear-mountedgroup NS. The sun wheel 11 can be fixed through a first switch element Aof the front-mounted group VS, wherein said element is designed as abrake. The planet carrier 25 with the planetary gears 22 is connected tothe ring gear 13, can be fixed through the third switch element Ddesigned as a brake, and can be connected to the drive shaft 1 throughthe fourth switch element E of the front-mounted group VS, wherein saidelement is designed as a clutch. The ring gear 23 is connected to theplanet carrier 15 of the planetary gears 12 and via the spacer shaft 2(speed nvs) to the ring gear 43. The sun wheels 31 and 41 are connectedto each other and can be fixed through a first switch element M of therear-mounted group NS that is designed as a brake. The planet carrier 45with the planetary gears 42 is connected to the ring gear 33, and theplanet carrier 35 of the planetary gears 32 is connected to the outputshaft 3 (speed nns).

[0063] By selectively switching the overall six switch elements A, B, D,E, M and H, pursuant to the shift logic shown in FIG. 2B a total of nineforward gears and one reverse gear R can be shifted. Particularly due tothe connection of the spacer shaft 2 to the ring gear 43 of the secondrear-mounted planetary gear set NS2, due to the coupled sun wheels 31,41 of the rear-mounted planetary gear sets NS1, NS2, wherein said wheelscan be fixed by the brake M, and due to the output through the planetcarrier 35 of the first rear-mounted planetary gear set NS1, theabove-described second design of the inventive multi-step reduction gearis suited in particular for applications with an output that is arrangedtransversely to the driving axle, for example, for a motor vehicle withfront-wheel drive and transverse driving motor. Another advantage ofsaid second design is that with a switched first gear in therear-mounted group NS no idle power arises.

[0064]FIGS. 3A and 3B show by way of example a third design of aninvented multi-step reduction gear, likewise with nine forward gears andone reverse gear, which is derived from the aforementioned first design.In the front-mounted group VS two shiftable, coupled front-mountedplanetary gear sets VS1 and VS2, as well as four switch elements A, B, Cand D are again provided; in the rear-mounted group NS it is twoshiftable, coupled rear-mounted planetary gear sets NS1 and NS2, as wellas two switch elements M and H.

[0065] The first shiftable front-mounted planetary gear set VS1 isdesigned here as a plus-transmission with double planetary gears andcomprises a sun wheel 11, a ring gear 13, a planet carrier 15′ withinterior planetary gears 12′, as well as a planet carrier 15″ withexterior planetary gears 12″, wherein both carriers 15′ and 15″ areconnected to each other. The second shiftable front-mounted planetarygear group VS2 comprises a sun wheel 21, a ring gear 23 and a planetcarrier 25 with planetary gears 22. The first rear-mounted group NS1comprises a sun wheel 31, a ring gear 33 and a planet carrier 35 withplanetary gears 32. The second rear-mounted group NS2 is designed as aplus-transmission with double planetary gears and comprises a sun wheel41, a ring gear 33, a planet carrier 45′ with interior planetary gears42′, as well as a planet carrier 45″ with exterior planetary gears 42″,wherein both planet carriers 45′ and 45″ are connected to each other.

[0066] As shown in FIG. 3A, the drive shaft 1 (speed n) can be connectedto the sun wheel 11 through a first clutch A of the front-mounted groupVS and to the sun wheel 21 through a second clutch B of thefront-mounted group NS. Moreover, the drive shaft 1 can be connected tothe coupled ring gears 33 and 43 by means of a second clutch H of therear-mounted group NS. The sun wheel 21 can be fixed through a thirdswitch element C of the front-mounted group VS, wherein said element isdesigned as a brake. The planet carrier 25 is connected to the coupledplanet carriers 15″ and 15′ and can be fixed through a fourth switchelement D of the front-mounted group VS that is designed as a brake.Furthermore, the ring gears 13 and 23 are coupled and connected to thesun wheel 41 by means of the spacer shaft 2 (speed nvs). The sun wheel31 can be fixed through a first switch element M of the rear-mountedgroup NS that is designed as a brake. The coupled planet carriers 45″and 45′ are connected to the planet carrier 35. The planet carrier 35 isin turn connected to the output shaft 3 (speed nns).

[0067] By selectively switching the overall six switch elements A, B, C,D, M and H pursuant to the shift logic shown in FIG. 3B, a total of nineforward gears and one reverse gear R can be shifted.

[0068] The following describes by way of example a fourth design of thepresent invention based on FIGS. 4A and 4B. Details that were alreadyexplained in connection with FIG. 1A have been marked identically inFIG. 4A. Compared to the first through third designs, the fourth designpursuant to the invention comprises in the front-mounted group VS afifth switch element E in addition to the four switch elements A throughD, with two switch elements M and H remaining unchanged in therear-mounted group NS. The coupling of the two front-mounted planetarygear groups VS1 and VS2 is identical to the first design, as is thecoupling of the two rear-mounted planetary gear sets NS1 and NS2.

[0069] As described in FIG. 4A, the planet carrier 25 of the planetarygears 22 is connected to the ring gear 13 and can be connected to thedrive shaft 1 (speed n) through a fifth clutch E of the front-mountedgroup VS and can be fixed with the brake D. The sun wheel 21 can beconnected to the drive shaft 1 through the clutch B and can be fixedwith the brake C. The sun wheel 11 can then be fixed through a firstswitch element of the front-mounted group A, wherein said element isdesigned as a brake. The planet carrier 15 is connected with theplanetary gears 12 to the ring gear 23 and via the spacer shaft 2 (speednvs) to the sun wheel 41. The planet carriers 45 are coupled with theplanetary gears 42 to the ring gear 33 and can be connected to the driveshaft 1 via the clutch H. The sun wheel 31 can be fixed through thebrake M. The planet carrier 35 is connected with the planetary gears 32to the ring gear 43 and the output shaft 3 (speed nns).

[0070] By selectively switching the seven switch elements A through E, Mand H pursuant to the shift logic shown in FIG. 4B, a total of elevenforward gears and one reverse gear R can be shifted. Beneficially, thisfourth design of the inventive multi-step reduction gear with four wheelsets can be used to create more gears compared to the priorstate-of-the-art, while simultaneously implementing a pressure supply tothe switch elements (four brakes) with a simple design.

[0071] Based on FIGS. 5A and 5B now a fifth exemplary design of aninventive multi-step reduction gear will be explained which is derivedfrom the fourth design. The front-mounted group VS, which is designed asa two-planet carrier/four-shaft transmission, again comprises fiveswitch elements A, B, C, D and E, one shiftable first front-mountedplanetary gear set VS1 with a sun wheel 11, a ring gear 13 and a planetcarrier 15 with planetary gears 12, as well as one shiftable secondfront-mounted planetary gear set VS2 with a sun wheel 21, a ring gear 23and a planet carrier 25 with planetary gears 22. The rear-mounted groupNS, which is also designed as a two-planet carrier/four-shafttransmission, comprises two switch elements M and H, one shiftable firstrear-mounted planetary gear set NS1 with a sun wheel 31, a ring gear 33and a planet carrier 35 with planetary gears 32, as well as oneshiftable second rear-mounted planetary gear set NS2 with a sun wheel41, a ring gear 43 and a planet carrier 45 with planetary gears 42.

[0072] Indifference from the fourth design, this fifth design of aninventive multi-step reduction gear has been modified in its componentcoupling within the rear-mounted group NS. The ring gear 33 of the firstrear-mounted planetary gear set NS1 and the planet carrier 45 of thesecond rear-mounted planetary gear set NS2 are coupled unchanged.Indifference from the fourth design, the sun wheels 31 and 41 of the tworear-mounted planetary gear sets NS1 and NS2 are now coupled; themechanical connection to the front-mounted group VS takes placeexclusively by means of the ring gear 43 of the second rear-mountedplanetary gear set NS2 and the output of the rear-mounted group NS bymeans of the planet carrier 35 of the first rear-mounted planetary gearset NS1.

[0073] One further difference of the fifth design of a multi-stepreduction gear pursuant to the invention results from designing thefirst switch element A of the front-mounted group VS as a clutch. Thesun wheel 11 of the first front-mounted planetary gear group VS1 can nowbe connected to the drive shaft 1 and can no longer be fixed.

[0074] As is shown in FIG. 5A, the ring gear 13 and the planet carrier25 are connected to each other, can be fixed with the fourth switchelement D of the front-mounted group VS and can be connected to thedrive shaft 1 by means of the fifth switch element E of thefront-mounted group VS. The ring gear 23 and the planet carrier 15 areconnected to each other and via the spacer shaft 2 to the ring gear 43.The ring gear 33 and the planet carrier 45 are connected to each otherand can be connected via the second switch element H of the rear-mountedgroup NS to the drive shaft 1. The planet carrier 35 is connected to theoutput shaft 3. The sun wheel 11 can be connected to the drive shaft 1via the first switch element A of the front-mounted group VS. The sunwheel 21 can be connected to the drive shaft 1 via the second switchelement B of the front-mounted group VS and can be fixed through thethird switch element C of the front-mounted group VS. The sun wheels 31and 41 are connected to each other and can be fixed by means of thefirst switch element M of the rear-mounted group NS.

[0075] As the switch logic pursuant to FIG. 5B shows, the selectiveshifting of the seven switch elements A through E, M and H allows atotal of eleven forward gears and one reverse gear R to be shifted. Asin the fourth design, this fifth design of the inventive multi-stepreduction gear can also beneficially be used to generate more gears withfour-wheel sets compared to the prior state-of-the-art.

[0076]FIG. 6A shows by way of example a sixth design of the inventivemulti-step reduction gear. In accordance with the switch logic depictedin FIG. 6B, a total of fifteen forward gears and one reverse gear can beshifted. The shiftable front-mounted planetary gear sets VS1 and VS2 aswell as the shiftable rear-mounted planetary gear sets NS1 and NS2 aredesigned like the corresponding wheel sets of the first and fourthdesigns of the inventive multi-step reduction gear and are also coupledto each other in the same manner. Indifference from the fourth design,however, the sixth design comprises one additional non-shiftablefront-mounted planetary gear group VSa, with an unchanged number ofswitch elements (five in the front-mounted group VS and two in therear-mounted group NS, now four clutches and three brakes).

[0077] As depicted in FIG. 6A, the additionalthird—non-shiftable—front-mounted planetary gear set Vsa comprises a sunwheel 11 a, a planet carrier 15 a′ with interior planetary gears 12 a′,a planet carrier 15 a″ with exterior planetary gears 12 a″, as well as aring gear 13 a. The sun wheel 11 a is fixed (speed zero) hereby. Theplanet carrier 15 a′ of the interior planetary gears 12 a′ and theplanet carrier 15 a″ of the exterior planetary gears 12 a″ are jointlyconnected to the drive shaft 1 (speed n). The ring gear 13 a rotates ata speed nva.

[0078] The planet carrier 25 with the planetary gears 22 of the secondshiftable front-mounted planetary gear group VS2 is connected to thering gear 13 of the first shiftable front-mounted planetary gear groupVS1, can be connected to the drive shaft 1 by means of the clutch E andcan be fixed with the brake D. The sun wheel 21 of the second shiftablefront-mounted planetary gear set VS2 can be connected via the clutch Bto the ring gear 13 a of the third front-mounted planetary gear set VSaand then rotates at a speed nva. Optionally, the sun wheel 21 can alsobe fixed by means of the brake C, wherein the clutch B and brake Cpursuant to the shift logic depicted in FIG. 6B are never actuatedsimultaneously. The sun wheel 11 of the first shiftable front-mountedplanetary gear set VS1 can be connected to the drive shaft 1 via thefirst switch element A of the front-mounted group VS, wherein saidelement is designed as a clutch. The planet carrier 15 with theplanetary gears 12 of the first shiftable front-mounted planetary geargroup VS1 is connected to the ring gear 23 of the second shiftablefront-mounted planetary gear set VS2 and via the spacer shaft 2 (speednvs) to the sun wheel 41 of the second rear-mounted planetary gear groupNS2. The planet carrier 45 with the planetary gears 42 of the secondrear-mounted planetary gear set NS2 is coupled to the ring gear 33 ofthe first rear-mounted planetary gear group NS1 and can be connected tothe drive shaft 1 by means of the second clutch H of the rear-mountedgroup NS. The sun wheel 31 of the first rear-mounted planetary geargroup NS1 can be fixed by means of the brake M of the rear-mounted groupNS. The planet carrier 35 with the planetary gears 32 of the firstrear-mounted planetary gear group NS1 is connected to the ring gear 43of the second rear-mounted planetary gear group NS2 and to the outputshaft 3 (speed nns).

[0079] The advantage compared to the aforementioned priorstate-of-the-art is that with the multi-step reduction gear with fivewheel sets and seven switch elements pursuant to the invention, moregears can be generated with comparatively identical design efforts.

[0080] In a further development of the sixth design of the multi-stepreduction gear pursuant to the invention, it can be provided that thethird front-mounted planetary gear group VSa is designed in a shiftablemanner. The second switch element B of the front-mounted group VS hereis not arranged between the ring gear 13 a of the third front-mountedplanetary gear set VSa and the sun wheel 21 of the second front-mountedplanetary gear group VS2, but either between the drive shaft 1 and thecoupled planet carriers 15 a′, 15 a″ of the third front-mountedplanetary gear group VSa or as a brake on the sun wheel 11 a of thethird front-mounted planetary gear set VSa. The ring gear 13 a and sunwheel 21 are then of course connected to each other.

[0081] Based on FIGS. 7A, 7B through 11A, 11B, further exemplary designsof an inventive multi-step reduction gear will now be described.Contrary to the aforementioned first six designs, in these furtherdesigns in addition to the second clutch H of the rear-mounted group NSa third switch element L of the rear-mounted group NS is connected tothe planet carrier of the second rear-mounted planetary gear group NS2.

[0082] As with the first through sixth designs of a multi-step reductiongear pursuant to the invention, in these seventh, tenth and eleventhdesigns, two switch elements in the front-mounted group VS and oneswitch element as well in the rear-mounted group NS are closed for thegears that are formed through front-mounted and rear-mounted groups.

[0083] Apart from the speed conditions 1 through 6 already mentioned,the following conditions additionally apply:

[0084] 8. the speed on the spider gear of the second rear-mountedplanetary gear group NS2, wherein said gear is connected to the spacershaft 2, is smaller than/equal to the speed nvs generated by thefront-mounted group VS with shifted switch elements L and M;

[0085] 9. the speed on the shifted switch element L is greaterthan/equal to zero and smaller than the input speed n of the drive shaft1; and

[0086] instead of the 7^(th) speed condition, the following applies:

[0087] 10. the speed on the shifted switch element M is greater thanzero and smaller than/equal to the input speed n of the drive shaft 1.

[0088] The seventh and tenth exemplary inventive designs of a multi-stepreduction gear each comprise identical mechanical component couplingswithin the front-mounted group VS and within the rear-mounted group NS.The eighth and ninth inventive designs each are derived from the seventhdesign, wherein different couplings within the front-mounted group VSand the rear-mounted group NS are incorporated. The eleventh inventeddesign is derived from the tenth design, as well, with differentcouplings within the front-mounted group VS and the rear-mounted groupNS. Of course, other mechanical couplings of the planetary gear setcomponents can also be provided in other further developments.

[0089]FIG. 7A now shows by way of example the gear pattern of a seventhdesign of an inventive multi-step reduction gear, comprising twoshiftable front-mounted planetary gear groups VS1, VS2, which arecoupled to a two-planet carrier/four-shaft transmission, and threeswitch elements A, B, D in the front-mounted group VS, as well ascomprising two shiftable rear-mounted planetary gear groups NS1, NS2,which are coupled to a two-planet carrier/four-shaft transmission, andthree switch elements M, H, L in the rear-mounted group NS. Byselectively closing the six switch elements, the configuration from FIG.7A allows the nine forward gears and one reverse gear as listed in thetable in FIG. 7B to be shifted. Three of the forward gears here aredesigned as overdrive gears.

[0090] As shown in FIG. 7A, the drive shaft 1 (speed n) can hereby becoupled to the sun wheel 21 of the second shiftable front-mountedplanetary gear set VS2 via the second clutch B of the front-mountedgroup VS, to the planet carrier 45 of the planetary gears 42 of thesecond rear-mounted planetary gear set NS2 via the second clutch H ofthe rear-mounted group NS, as well as to the sun wheel 31 of the firstrear-mounted planetary gear set NS1 via the first clutch M of therear-mounted group NS. The planet carrier 25 with the planetary gears 22of the second shiftable front-mounted planetary gear set VS2 and thering gear 13 of the first shiftable front-mounted planetary gear set VS1are coupled and can be fixed by means of the third switch element D ofthe front-mounted group VS, wherein said element is designed as a brake.The sun wheel 11 of the first shiftable front-mounted planetary gear setVS1 can be fixed by means of the first switch element A of thefront-mounted group VS, wherein said element is designed as a brake. Theplanet carrier 15 with the planetary gears 12 of the first shiftablefront-mounted planetary gear set VS1 is connected to the ring gear 23 ofthe second shiftable front-mounted planetary gear set VS2 and connectedto the sun wheel 41 of the second rear-mounted planetary gear group NS2via the spacer shaft 2 (speed nvs). The planet carrier 45 with theplanetary gears 42 of the second shiftable rear-mounted planetary gearset NS2 is coupled to the ring gear 33 of the first rear-mountedplanetary gear set NS1 and can be fixed by means of the third switchelement L of the rear-mounted group NS, wherein said element is designedas a brake. The planet carrier 35 with the planetary gears 32 of thefirst rear-mounted planetary gear set NS1 is connected to the ring gear43 of the second rear-mounted planetary gear set NS2 and connected tothe drive shaft 3 (speed nns).

[0091] Contrary to the aforementioned prior state-of-the-art, theseventh design of an inventive multi-step reduction gear depicted inFIGS. 7A, 7B has the same advantage as the first design pursuant toFIGS. 1A and 1B. Compared to the first design, the gear stepconfiguration of the seventh design is more advantageous.

[0092] A further development of the seventh design of an inventivemulti-step reduction gear suggests designing the second switch element Bof the shiftable front-mounted group VS as a brake connected it to thespacer shaft 2. The appropriate gear pattern is depicted in FIG. 7C.Here the brake B is connected to the planet carrier 15 of the firstfront-mounted planetary gear set VS1 and therefore simultaneously to thering gear 23 of the second front-mounted planetary gear set VS2, as wellas with the spacer shaft 2. The sun wheel 21 of the second front-mountedplanetary gear set VS2 is connected to the drive shaft 1.

[0093] Apart from that, the diagrammatic transmission design correspondsto that of the fourth design. Thus, four of the total of six switchelements are beneficially designed as brakes, with the familiar designadvantages regarding their compressed oil supply.

[0094]FIG. 7D shows the shift logic of this further development of theseventh design of an inventive multi-step reduction gear. As with theseventh design, nine forward gears and one reverse gear can be shifted.

[0095] In FIGS. 8A and 8B an eighth exemplary design of an inventivemulti-step reduction gear is explained, which is derived from theseventh design and comprises three switch elements A, B, D and twoshiftable front-mounted planetary gear sets VS1, VS2 in thefront-mounted group VS, as well as three switch elements M, H, L and twoshiftable rear-mounted planetary gear sets NS1, NS2 in the rear-mountedgroup. Contrary to the seventh design described above in FIG. 7A, allthree switch elements A, B, D of the front-mounted group VS are nowdesigned as brakes and the component coupling within the front-mountedgroup VS and within the rear-mounted group NS has been modified. Thesecond shiftable front-mounted planetary gear set VS2 and the firstshiftable rear-mounted planetary gear set NS1 are now designed asplus-transmissions. The output of the front-mounted group VS (speed nvs)remains unchanged and is connected rigidly to a spider gear of therear-mounted group NS via the spacer shaft 2, as is the case in theseventh design with the sun wheel 41 of the second rear-mountedplanetary gear set NS2.

[0096] As shown in FIG. 8A, the first shiftable front-mounted planetarygear set VS1 comprises a sun wheel 11, a ring gear 13 and a planetcarrier 15 with planetary gears 12. The second shiftable front-mountedplanetary gear set VS2 is designed as a double-planetary gear set andcomprises a sun wheel 21, a ring gear 23 and two coupled planet carriers25′, 25″ with interior and exterior planetary gears 22′, 22″. The sunwheel 11 can be fixed by means of the brake A. The sun wheel 21 isconnected to the drive shaft 1. The ring gears 13 and 23 are connectedto each other and can be fixed by means of the brake D. The planetcarriers 15, 25′, 25″ are connected to one another and can be fixed withthe brake B. Moreover, the coupled planet carriers 15, 25′, 25″ form theoutput of the front-mounted group VS (speed nvs) and are connectedfirmly to a sun wheel 41 of the second rear-mounted planetary gear setNS2 via the spacer shaft 2. The first rear-mounted planetary gear setNS1 is designed as a double-planetary gear set and comprises a sun wheel31, a ring gear 33 and two coupled planet carriers 35′, 35″ withinterior and exterior planetary gears 32′, 32″. The second rear-mountedplanetary gear set NS2 comprises the sun wheel 41, a ring gear 43 and aplanet carrier 45 with planetary gears 42. The sun wheel 31 can beconnected to the drive shaft 1 by means of the first switch element M ofthe rear-mounted group NS, wherein said element is designed as a clutch.The planet carriers 35′, 35″ and 45 are connected to one another, can beconnected to the drive shaft 1 via the second switch element H of therear-mounted group NS designed as a clutch, and can be fixed by means ofthe third switch element L of the rear-mounted group NS designed as abrake. The ring gears 33 and 43 are connected to each other andsimultaneously form the output of the rear-mounted group NS (speed nns),and are thus connected to the output shaft 3.

[0097] As with the seventh design, also in the eighth design of aninventive multi-step reduction gear described above a total of nineforward gears and one reverse gear can be shifted without multipleconnections by selectively shifting the six switch elements A, B, D andM, H, L, as depicted in FIG. 8B.

[0098] In FIGS. 9A and 9B a ninth exemplary design of an inventivemulti-step reduction gear is explained, which is likewise derived fromthe seventh design and comprises three switch elements A, B, D and twoshiftable front-mounted planetary gear sets VS1, VS2 in thefront-mounted group VS, as well as three switch elements M, H, L and twoshiftable rear-mounted planetary gear sets NS1, NS2 in the rear-mountedgroup. Contrary to the seventh design described previously in FIG. 7A,all three switch elements A, B, D of the front-mounted group VS aredesigned as brakes and the component coupling has been modified withinthe front-mounted group VS and within the rear-mounted group NS. Theoutput of the front-mounted group VS (speed nvs) remains unchanged andis connected rigidly to a spider gear of the rear-mounted group NS viathe spacer shaft 2, differently from the seventh design, however, withthe ring gear 43 of the second rear-mounted planetary gear set NS2.

[0099] As shown in FIG. 9A, the first shiftable front-mounted planetarygear set VS1 comprises a sun wheel 11, a ring gear 13 and a planetcarrier 15 with planetary gears 12. The second shiftable front-mountedplanetary gear set VS2 comprises a sun wheel 21, a ring gear 23 and aplanet carrier 25 with planetary gears 22. The sun wheels 11 and 21 areconnected to each other and can be fixed by means of the brake A. Thering gear 23 is connected to the drive shaft 1. The ring gear 13 and theplanet carrier 25 are connected to each other and can be fixed by meansof the brake D. The planet carrier 15 can be fixed with the brake B.Moreover, the planet carrier 15 forms the output of the front-mountedgroup VS (speed nvs) and is connected firmly to a ring gear 43 of thesecond rear-mounted planetary gear set NS2 via the spacer shaft 2. Thefirst rear-mounted planetary gear set NS1 comprises a sun wheel 31, aring gear 33 and a planet carrier 35 with planetary gears 32. The secondrear-mounted planetary gear set NS2 comprises a sun wheel 41, the ringgear 43 and a planet carrier 45 with planetary gears 42. The sun wheels31 and 41 are connected to each other and can be connected to the driveshaft 1 by means of the first switch element M of the rear-mounted groupNS, wherein said element is designed as a clutch. The ring gear 33 andthe planet carrier 45 are connected to each other, can be connected tothe drive shaft 1 via the second switch element H of the rear-mountedgroup NS designed as a clutch, and can be fixed by means of the thirdswitch element L of the rear-mounted group NS designed as a brake. Theplanet carrier 35 forms the output of the rear-mounted group NS (speednns), and is thus connected to the output shaft 3.

[0100] As in the seventh design, as well as in the ninth design of aninventive multi-step reduction gear described above, a total of nineforward gears and one reverse gear can be shifted without multipleconnection by selectively shifting the six switch elements A, B, D andM, H, L pursuant to the shift logic depicted in FIG. 9B. Herein, as isalso the case with the designs described in FIGS. 7C and 8A, only twoswitch elements are closed in each shifted gear. Compared to the seventhdesign, the spread is slightly enlarged and the component coupling ofthe rear-mounted group NS is more favorable in the first gear withregard to idle power.

[0101] An exemplary tenth design of an inventive multi-step reductiongear described pursuant to FIG. 10A comprises, compared to the seventh,eighth and ninth designs, a fourth switch element E, which is designedas a clutch, in the front-mounted group VS. By selectively shifting theseven switch elements A, B, D, E and H, M, L, a total of eleven forwardgears and three reverse gears can be shifted pursuant to the shift logicdepicted in FIG. 10B.

[0102] As shown in FIG. 10A, the first and third switch elements A, D ofthe front-mounted group VS are designed as brakes, the second and fourthswitch elements B, E of the front-mounted group VS as clutches. Thefirst and the second switch elements M, H of the rear-mounted group NSare clutches, the third switch element L of the rear-mounted group NS isa brake.

[0103] The drive shaft 1 (speed n) can hereby be connected to the sunwheel 21 of the second shiftable front-mounted planetary gear set VS2via the clutch B, to the planet carrier 45 of the planetary gears 42 ofthe second rear-mounted planetary gear set NS2 via the clutch H, to thesun wheel 31 of the first rear-mounted planetary gear set NS1 via theclutch M, as well as to the planet carrier 25 of the planetary gears 22of the second shiftable front-mounted planetary gear set VS2 via theclutch E. The planet carrier 25 are coupled with the planetary gears 22of the second shiftable front-mounted planetary gear set VS2 and thering gear 13 of the first shiftable front-mounted planetary gear set VS1and can be fixed by means of the brake D. The sun wheel 11 of the firstshiftable front-mounted planetary gear set VS1 can be fixed by means ofthe brake A.

[0104] The planet carrier 15 with the planetary gears 12 of the firstshiftable front-mounted planetary gear set VS1 is connected to the ringgear 23 of the second shiftable front-mounted planetary gear group VS2and via the spacer shaft 2 (speed nvs) to the sun wheel 41 of the secondrear-mounted planetary gear set NS2. The planet carrier 45 with theplanetary gears 42 of the second rear-mounted planetary gear set NS1 iscoupled to the ring gear 33 of the first rear-mounted planetary gear setNS1 and can be fixed by means of the brake L. The planet carrier 35 withthe planetary gears 32 of the first rear-mounted planetary gear groupNS1 is connected to the ring gear 43 of the second rear-mountedplanetary gear group NS2 and to the output shaft 3 (speed nns).

[0105] It is beneficial compared to the described prior state-of-the-artthat more gears can be produced with four wheel sets through theinventive multi-step reduction gear pursuant to FIGS. 10A, 10B. Comparedto the fourth and fifth designs of the inventive multi-step reductiongear, up to three reverse gears can be shifted beneficially. A specialreverse gear, which is “longer” compared to the “normal” reverse gear,can be included, for example, in a winter driving program for theautomatic transmission. An additional reverse gear that is “shorter”compared to the “normal” reverse gear is favorable, for example, foroff-road vehicles or for a trailer operation of the vehicle.

[0106]FIGS. 11A and 11B explain an eleventh exemplary design of aninventive multi-step reduction gear, which is derived from the tenthdesign. In the front-mounted group VS four switch elements A, B, C, Dand two coupled, shiftable front-mounted planetary gear sets VS1 and VS2are again provided, as well as three switch elements M, H, L and twocoupled, shiftable rear-mounted planetary gear sets NS1 and NS2 in therear-mounted group. Indifference from the above-described tenth design,the first switch element A of the front-mounted group VS is now aclutch, and the fourth switch element D of the front-mounted group VS isa brake. For reasons of consistent nomenclature, the third and fourthswitch elements in the eleventh design have been marked C and D sincethe designation “E” thus far, as well as in the following designs ofmulti-step reduction gears pursuant to the invention, has been and isused for a clutch. Further differences from the tenth design relate tothe component coupling within the front-mounted group VS and within therear-mounted group NS.

[0107] As shown in FIG. 11A, the sun wheel 11 of the first front-mountedplanetary gear set VS1 can be connected to the drive shaft 1 via thefirst switch element A of the front-mounted group VS, wherein saidelement is designed as a clutch. The sun wheel 21 of the secondfront-mounted planetary gear set VS2 can be connected to the drive shaft1 via the second switch element B of the front-mounted group VS, whereinsaid element is designed as a clutch, and can be fixed through the thirdswitch element C of the front-mounted group VS designed as a brake. Thering gear 13 of the first front-mounted planetary gear set VS1 and theplanet carrier 25 of the second front-mounted planetary gear set VS2 areconnected to each other and can be fixed by means of the fourth switchelement D of the front-mounted group VS designed as a brake. The ringgear 23 of the second front-mounted planetary gear set VS2 and theplanet carrier 15 of the first front-mounted planetary gear set VS1 areconnected to each other to form the output of the front-mounted groupVS, and are connected by means of the spacer shaft 2 (speed nvs) to thesun wheel 41 of the second rear-mounted planetary gear set NS2 and thering gear 33 of the first rear-mounted planetary gear set NS1, whereinsaid gear is coupled to said sun wheel 41. The sun wheel 31 of the firstrear-mounted planetary gear set NS1 can be connected to the drive shaft1 via the first switch element M of the rear-mounted group NS, whereinsaid element is designed as a clutch. The planet carriers 35, 45 of theplanetary gears 32, 43 of both rear-mounted planetary gear sets NS1, NS2are connected to each other, can be connected to the drive shaft 1 bymeans of the second switch element H of the rear-mounted group NS,wherein said element is designed as a clutch, and can be fixed with thethird switch element L of the rear-mounted group NS designed as a brake.The ring gear 43 of the second rear-mounted planetary gear set NS2 formsthe output of the rear-mounted group NS and is connected to the outputshaft 3.

[0108] As is shown in the shift logic depicted in FIG. 11A, in thedescribed eleventh design of a multi-step reduction gear pursuant to theinvention—just as with the tenth design—a total of eleven forward gearsand three reverse gears can be shifted without multiple connection byselectively shifting the switch elements A, B, C, D, M, H, L, withharmonious gear steps and large spread.

[0109] In a twelfth design of an inventive multi-step reduction gear itis suggested, by way of example for the second solution of the taskpursuant to the invention, to form the front-mounted group VS from twoshiftable front-mounted planetary gear sets VS1 and VS2, which areindependent from each other, i.e., not coupled, which is different fromthe coupled front-mounted planetary gear sets pursuant to the designsone through eleven explained above. On the output side, thefront-mounted group VS of the twelfth design is unchanged and isconnected to the spacer shaft 2.

[0110]FIG. 12A then shows the gear pattern of the twelfth design of aninventive multi-step reduction gear. Overall, five switch elements areprovided: the brake A, and clutch B in the front-mounted group VS, aswell as the clutch M, clutch H and brake L in the rear-mounted group NS.The sun wheel 11 of the first shiftable front-mounted planetary gear setVS1 is connected directly to the drive shaft 1 (speed n). The sun wheel21 of the second shiftable front-mounted planetary gear set VS2 can beconnected to the drive shaft 1 through the clutch B. The drive shaft 1can be connected to the sun wheel 31 of the first rear-mounted planetarygear set NS1 via the clutch M and to the planet carrier 45 of the secondrear-mounted planetary gear set NS2 via the clutch H. The planet carrier25 is firmly connected to the housing with the planetary gears 22 of thesecond shiftable front-mounted planetary gear set VS2, i.e., it isfixed. The ring gear 13 of the first shiftable front-mounted planetarygear set VS2 can be fixed by means of the brake planet carrier 25 of thesecond front-mounted planetary gear set VS2. The planet carrier 15 ofthe first shiftable front-mounted planetary gear set VS1 and the ringgear 23 of the second front-mounted planetary gear set VS2 are coupledto each other and connected to the sun wheel 41 of the secondrear-mounted planetary gear set NS2 by means of the spacer shaft 2(speed nvs). The planet carrier 45 of the second rear-mounted planetarygear set NS2 is coupled to the ring gear 33 of the first rear-mountedplanetary gear set NS1 and can be fixed by means of the brake L. Thering gear 43 of the second rear-mounted planetary gear set NS2 isconnected to the planet carrier 35 of the first rear-mounted planetarygear set NS1 and to the output shaft 2 (speed nvs).

[0111] By selectively shifting the five switch elements A, B and H, Mand L, pursuant to the shift logic shown in FIG. 12B, a total of sevenforward gears and one reverse gear can be shifted. The output speed nvsof the front-mounted group VS is hereby generated by closing only oneswitch element (A or B) of the front-mounted group VS.

[0112] Compared to the aforementioned prior state-of-the-art, thetwelfth design of the inventive multi-step reduction gear beneficiallycomprises two brakes as switch elements, the compressed oil or fluidsupply of which can be designed in a simple manner for actuationpurposes and therefore cost-effectively.

[0113] The following describes further designs of an inventivemulti-step reduction gear that are designed without a shiftable reversegear and that are suited especially for bicycles, motorcycles andmulti-gear special purpose vehicles.

[0114] Herewith in the forward gears, which are formed withfront-mounted and rear-mounted groups, two switch elements in thefront-mounted group VS and one switch element in the rear-mounted groupNS are closed, respectively. In the forward gears, which are formed onlywith the rear-mounted group NS, a maximum of one switch element of thenext higher or next lower gear is always closed in the front-mountedgroup VS.

[0115]FIG. 13A now shows by way of example a thirteenth design of aninventive multi-step reduction gear, which with regard to the number ofwheel sets and switch elements in the front-mounted and rear-mountedgroups is comparable to the sixth design of an inventive multi-stepreduction gear described above. In this thirteenth design, however, thesmallest speed on the spacer shaft 2, i.e., the output speed nvs of thefront-mounted group, is always positive with a positive input speed n.

[0116] As is shown in FIG. 13A, the front-mounted group VS comprises twocoupled, shiftable front-mounted planetary gear sets VS1 and VS2, athird, non-shiftable front-mounted planetary gear set VSA, as well asfour clutches A, B, D, E and one brake C, the shiftable rear-mountedgroup NS comprises two coupled rear-mounted planetary gear sets NS1 andNS2, as well as one brake M and one clutch H. The front-mounted group VSand rear-mounted group NS are connected to each other by means of thespacer shaft 2.

[0117] The drive shaft 1 (speed n) is connected to the ring gear 13 a ofthe third front-mounted planetary gear set VSA, as well as to the planetcarrier 25 of the planetary gears 22 of the second shiftablefront-mounted planetary gear set VS2 via the clutch E, to the ring gear13 of the first shiftable front-mounted planetary gear set VS1 via theclutch A and to the planet carrier 45 of the planetary gears 42 of thesecond rear-mounted planetary gear set NS2 via the clutch H. Theplanetary gears 12 a of the third front-mounted planetary gear set VSAare designed as stepped planetary gear systems with small planet gears12 ak and large planet gears 12 ag. The planet carrier 15 a (speed nva)with the planet gears 12 ak and 12 ag of the third front-mountedplanetary gear group VSA can be connected to the sun wheel 21 of thesecond shiftable front-mounted planetary gear set VS2 by means of theclutch B and to the planet carrier 25 of the planetary gears 22 of thesecond shiftable front-mounted planetary gear set VS2 by means of theclutch D. The ring gear 13 a of the third front-mounted planetary gearset VSA engages the large planet gears 12 ag of the third front-mountedplanetary gear set VSA. The sun wheel 11 a of the third front-mountedplanetary gear set VSA is fixed and engages with the small planet gears12 ak of the third front-mounted planetary gear set VSA. The sun wheel21 of the second shiftable front-mounted planetary gear set VS2 isconnected to the sun wheel 11 of the first shiftable front-mountedplanetary gear set VS1 and can be fixed by means of the brake C. Thering gear 13 of the first shiftable front-mounted planetary gear set VS1is connected to the ring gear 23 of the second shiftable front-mountedplanetary gear set VS2. The planet carrier 15 with the planetary gears12 of the first shiftable front-mounted planetary gear set VS1 isconnected to the sun wheel 41 of the second rear-mounted planetary gearset NS2 by means of the spacer shaft 2 (speed nvs) and to the ring gear33 of the first rear-mounted planetary gear set NS1. The planet carrier45 with the planetary gears 42 of the second rear-mounted planetary gearset NS2 are coupled with the planet carrier 35 with the planetary gears35 of the first rear-mounted planetary gear set NS1, i.e., connected toeach other. The sun wheel 31 of the first rear-mounted planetary gearset NS1 can be fixed by means of the brake M. The ring gear 43 of thesecond rear-mounted planetary gear set NS2 is connected to the outputshaft 3 (speed nns).

[0118] By selectively switching the seven switch elements A through E, Hand M—pursuant to the shift logic shown in FIG. 13B—a total of seventeenforward gears can be shifted without multiple connection. A reverse gearis not provided. The advantage over the prior state-of-the-art is thatthe seventeen forward gears are realized with one less switch elementand one less wheel set.

[0119] In FIGS. 14A and 14B, an exemplary fourteenth design of aninventive multi-step reduction gear is explained, which is derived fromthe thirteenth design. The design of the rear-mounted group NS, forexample, is identical, as are the type and number of switch elements inthe front-mounted group and the number of wheel sets in thefront-mounted group VS. The number of gears that can be shifted withoutmultiple connections is also accordingly identical, as can be seen fromthe shift logic in FIG. 14B. The component coupling within the first andsecond front-mounted planetary gear sets VS1 and VS2 has been modified,as has the design of the third, non-shiftable front-mounted planetarygear set VSa.

[0120] As shown in FIG. 14A, the non-shiftable third front-mountedplanetary gear set VSA is now implemented as a plus-transmission indouble-planet design and comprises a sun wheel 11 a, a ring gear 13 aand two coupled planet carriers 15 a′, 15 a″ with interior and exteriorplanet gears 12 a′, 12 a″. The sun wheel 11 a is fixed. The coupledplanet carriers 15 a′, 15 a″ are connected to the drive shaft 1. Thering gear 13 a can be connected to the sun wheel 21 of the secondfront-mounted planetary gear set VS2 by means of the second switchelement B of the front-mounted group VS, wherein said element isdesigned as a clutch. Moreover, the ring gear 13 a can be connected tothe planet carrier 25 of the second front-mounted planetary gear set VS2by means of the fourth switch element D of the front-mounted group VS,wherein said element is designed as a clutch. Said planet carrier 25 inturn is connected to the ring gear 13 of the first front-mountedplanetary gear set VS1 and can be connected to the drive shaft 1 bymeans of the fifth switch element E of the front-mounted group VSdesigned as a clutch. The sun wheel 21 can also be fixed with the thirdswitch element C of the front-mounted group VS designed as a brake. Thering gear 23 of the second front-mounted planetary gear set VS2 iscoupled to the sun wheel 11 of the first front-mounted planetary gearset VS1 and can be connected by means of the first switch element A ofthe front-mounted group VS designed as a clutch. The planet carrier 15of the first front-mounted planetary gear set VS1 forms the output ofthe front-mounted group VS and is connected to the spacer shaft 2 (speednvs). On the rear-mounted group side, the spacer shaft 2 is connected tothe sun wheel 41 of the second rear-mounted planetary gear set NS2 andthe ring gear 33 of the first rear-mounted planetary gear set NS1, i.e.,coupled to said sun wheel 41. The planet carriers 35 and 45 of the tworear-mounted planetary gear sets NS1 and NS2 are coupled and can beconnected to the drive shaft 1 by means of the second switch element Hof the rear-mounted group NS designed as a clutch. The sun wheel 31 ofthe first rear-mounted planetary gear set NS1 can be fixed with thefirst switch element M of the rear-mounted group NS, wherein saidelement is designed as a brake. The ring gear 43 of the secondrear-mounted planetary gear set NS2 forms the output of the rear-mountedgroup NS (speed nns) and is connected to the output shaft 3.

[0121] Similar to the thirteenth design, the fourteenth design of amulti-step reduction gear pursuant to the invention described above isalso particularly suited for a vehicle or bicycle application with inputand output arranged transversely in the direction of travel, but alsofor a driving device with output that is arranged transversely to theinput.

[0122]FIG. 15A shows, by way of example, a fifteenth design of amulti-step reduction gear pursuant to the invention, which with regardto the number of switch elements in the rear-mounted group NS iscomparable to the seventh through eleventh designs of the inventivemulti-step reduction gear. Overall, eight switch elements are provided,of which seven are clutches and one is a brake, as well as fiveplanetary gear sets. The shiftable front-mounted group VS comprises twocoupled, shiftable front-mounted planetary gear sets VS1 and VS2, athird, non-shiftable front-mounted planetary gear set VSa, four clutchesA, B, D and E, and as a brake C. The third front-mounted planetary gearset VSA here takes on a double-planetary wheel design, with interiorplanetary gears 12 a′ and exterior planetary gears 12 a″ and accordinglytwo planet carriers 15 a′ and 15 a″. The shiftable rear-mounted group NScomprises two coupled rear-mounted planetary gear groups NS1, NS2 aswell as three clutches M, H, L. The front-mounted group VS andrear-mounted group NS are connected to each other by means of the spacershaft 2.

[0123] The drive shaft 1 (speed n) is hereby connected to the sun wheel11 a of the third front-mounted planetary gear set VSA, as well as tothe sun wheel 11 of the first shiftable front-mounted planetary gear setVS1 via the clutch A, to the planet carrier 25 of the planetary gears 22of the second shiftable front-mounted planetary gear set VS2 via theclutch E and to the planet carrier 45 of the planetary gears 42 of thesecond rear-mounted planetary gear set NS2 via the clutch H. The planetcarrier 15 a′ of the interior planetary gears 12 a′ of the thirdfront-mounted planetary gear group VSA and the planet carrier 15 a″ ofthe exterior planetary gears 12 a″ of the third front-mounted planetarygear group VSA are coupled and fixed. The sun wheel 21 of the secondshiftable front-mounted planetary gear set VS2 can be fixed by means ofthe brake C with the planet carrier 15 a″ of the exterior planet gears12 a″ of the third front-mounted planetary gear set VSA. The ring gear13 a (speed nva) of the third front-mounted planetary gear set VSA canbe connected to the sun wheel 21 of the second shiftable front-mountedplanetary gear set VS2 by means of the clutch B, to the planet carrier25 of the planetary gears 22 of the second shiftable front-mountedplanetary gear set VS2 by means of the clutch D, to the planet carrier45 of the planetary gears 42 of the second rear-mounted planetary gearset NS2 by means of the clutch L and to the sun wheel 31 of the firstrear-mounted planetary gear set NS1 by means of the clutch M. The planetcarrier 25 with the planetary gears 22 of the second shiftablefront-mounted planetary gear set VS2 and the ring gear 13 of the firstshiftable front-mounted planetary gear set VS1 are coupled with eachother. The sun wheel 11 of the first shiftable front-mounted planetarygear set VS1 and the ring gear 23 of the second shiftable front-mountedplanetary gear set VS2 are likewise coupled to each other. The planetcarrier 15 (speed nvs) with the planet gears 12 of the first shiftablefront-mounted planetary gear set VS1 is connected to the sun wheel 41 ofthe second rear-mounted planetary gear set NS2 via the spacer shaft 2.The planet carrier 45 with the planet gears 42 of the secondrear-mounted planetary gear set NS2 is connected to the ring gear 33 ofthe first rear-mounted planetary gear set NS1. The planet carrier 35with the planet gears 32 of the first rear-mounted planetary gear setNS1 is connected to the ring gear 43 of the second rear-mountedplanetary gear set NS2 and to the output shaft 3 (speed nns).

[0124] By selectively switching the eight switch elements A through Eand H, M and L, pursuant to the shift logic shown in FIG. 15B, a totalof twenty-four forward gears can be shifted. A reverse gear is notprovided. The advantage of this fifteenth design of an inventivemulti-step reduction gear over the aforementioned prior state-of-the-artis that overall, twenty-four instead of seventeen forward gears arerealized with the same number of switch elements and one less wheel set.

[0125] In an exemplary sixteenth design of a multi-step reduction gearpursuant to the invention, it is suggested to provide in thefront-mounted group VS two coupled shiftable front-mounted planetarygear sets VS1 and VS2, as well as two additional coupled, non-shiftablefront-mounted planetary gear sets VSA and VSb. FIG. 16A shows theappropriate shift pattern. As with the fifteenth design of the inventivemulti-step reduction gear, five switch elements A, B, C, D, E designedas clutches are provided in the front-mounted group VS and three switchelements M, H and L designed as clutches in the rear-mounted group NS.

[0126] As depicted in FIG. 16A, the drive shaft 1 (speed n) is connectedto the sun wheel 11 b of the fourth front-mounted planetary gear setVSb, as well as to the sun wheel 21 of the second shiftablefront-mounted planetary gear set VS2 via the clutch B, to the planetcarrier 25 of the planetary gears 22 of the second shiftablefront-mounted planetary gear set VS2 via the clutch E and to the planetcarrier 45 of the planetary gears 42 of the second rear-mountedplanetary gear set NS2 via the clutch H. The sun wheel 11 a of the thirdfront-mounted planetary gear set VSA is fixed.

[0127] The fourth front-mounted planetary gear set VSb is designed as adouble-planetary gear group. The planet carrier 15 a (speed nva) withthe planet gears 12 a of the third front-mounted planetary gear set VSAis connected to the planet carrier 15 b″ of the exterior planet gears 12b″ of the fourth front-mounted planetary gear set VSb and the planetcarrier 15 b′ of the interior planet gears 12 b′ of the fourthfront-mounted planetary gear set (VSb). Moreover, the planet carrier 15a of the third front-mounted planetary gear set VSA can be connected tothe sun wheel 21 of the second shiftable front-mounted planetary gearset VS2 by means of the clutch C, to the planet carrier 25 of theplanetary gears 22 of the second shiftable front-mounted planetary gearset VS2 by means of the clutch D and to the planet carrier 35″ of theexterior planet gears 32″ of the first rear-mounted planetary gear setNS1 by means of the clutch L. The planet gears 12 a of the thirdfront-mounted planetary gear set VSA and the planet gears 12 b″ of thefourth front-mounted planetary gear set VSb are hereby grouped. The ringgear 13 a (speed nvb) of the third front-mounted planetary gear set VSAand the ring gear 13 b of the fourth front-mounted planetary gear setVSb are coupled with each other. Both ring gears 13 a and 13 b can beconnected to the sun wheel 11 of the first shiftable front-mountedplanetary gear set VS1 by means of the clutch A and to the sun wheel 31of the first rear-mounted planetary gear set NS1 by means of the clutchM. The sun wheel 11 of the first shiftable front-mounted planetary gearset VS1 is connected to the ring gear 23 of the second shiftablefront-mounted planetary gear set VS2. The planet carrier 25 with theplanet gears 22 of the second shiftable front-mounted planetary gear setVS2 is connected to the ring gear 13 of the first shiftablefront-mounted planetary gear set VS1. The planet carrier 15 with theplanet gears 12 of the first shiftable front-mounted planetary gear setVS1 is connected to the sun wheel 41 of the second rear-mountedplanetary gear set NS2 via the spacer shaft 2 (speed nvs). The planetcarrier 35″ with the exterior planet gears 32″ of the first rear-mountedplanetary gear set NS1 and the planet carrier 35′ with the interiorplanet gears 32′ of the first rear-mounted planetary gear set NS1 andthe planet carrier 45 of the planet gears 42 of the second rear-mountedplanetary gear set NS2 are connected with each other. The exteriorplanet gears 32″ of the first rear-mounted planetary gear set NS1 andthe planet gears 42 of the second rear-mounted planetary gear set NS2are hereby grouped. The ring gears 33 and 43 of the first and secondrear-mounted planetary gear groups NS1, NS2 are connected with eachother and additionally with the output shaft 3 (speed nns).

[0128] By selectively shifting the eight switch elements A through E andH, M and L, pursuant to the shift logic shown in FIG. 16B, a total oftwenty-six forward gears can be shifted. A reverse gear is not provided.Over the prior state-of-the-art, with this sixteenth design of aninventive multi-step reduction gear realizes twenty-six instead ofseventeen forward gears with the same number of switch elements andwheel sets.

[0129] Due to the extremely compact design of the transmission and theelimination of the reverse gear, designs thirteen through sixteen of amulti-step reduction gear pursuant to the invention are particularlysuited as hub shifting systems for bicycles.

[0130] Through the appropriate selection of gear ratios of theindividual planetary gear sets, the fifteenth and sixteenth designs ofthe inventive multi-step reduction gear can also be used to derive amulti-step reduction gear with one, two or several reverse gears,respectively. Hereby the number of forward gears is reduced by thenumber of reverse gears, respectively. Such further developments of theinventive multi-step reduction gear are particularly suitable formulti-gear special-purpose drives.

[0131] In a further development of the invention it is suggested toinstall a second rear-mounted group NS′ behind the rear-mounted groupNS. This way—proceeding on the aforementioned multi-step reduction gearspursuant to the invention—very compact multi-gear transmissions can bederived with just a few additional components. Pursuant to theinvention, it is suggested to design this second rear-mounted group NS′in a shiftable manner, with two further coupled rear-mounted planetarygear sets NS1′, NS2′ and two further switch elements M′, H′. The secondrear-mounted group NS′ can hereby be connected on the input side on onehand to the drive shaft 1 (speed n) of the transmission via one of itsswitch elements and on the other hand is firmly connected to the outputshaft 3 (speed nns) of the rear-mounted group NS for generating anoutput speed (nns′).

[0132] Based on FIGS. 17A, 17B and 17C, 17D, two designs pursuant to theinvention of a second rear-mounted group NS′ will now be explained astwo-planet carrier/four-shaft transmissions, with a first switch elementM′ designed as a brake and a second switch element H′ designed as aclutch.

[0133]FIG. 17A depicts a first design of an inventive secondrear-mounted group NS′ with two coupled rear-mounted planetary gear setsNS1′, NS2′, which can be shifted by means of the switch elements M′, H′.The first rear-mounted planetary gear set NS1′ of the secondrear-mounted group NS1 hereby comprises a sun wheel 51, a ring gear 53and a planet carrier 55 with planet gears 52, the second rear-mountedplanetary gear set NS2′ of the second rear-mounted group NS′ comprises asun wheel 61, a ring gear 63 and a planet carrier 65 with planet gears62. The sun wheels 51 and 61 are connected to each other and can befixed by means of the brake M′. The ring gear 53 and the planet carrier65 are connected to each other and can be connected to the drive shaft 1(speed n) of the transmission by means of the clutch H′. The ring gear63 is connected to the output of the rear-mounted group NS via theoutput shaft 3 (speed nns). The planet carrier 55 forms the output ofthe second rear-mounted group NS′ and is connected to an output shaft 4(speed nns′) of the transmission.

[0134]FIG. 17B shows exemplary standing gear ratios of this first designof a second rear-mounted group NS′ pursuant to the invention.

[0135]FIG. 17C depicts a second design of an inventive secondrear-mounted group NS′ with two coupled rear-mounted planetary gear setsNS1′, NS2′, which can be shifted by means of the switch elements M′, H′.The first rear-mounted planetary gear set NS1′ of the secondrear-mounted group NS′ hereby comprises a sun wheel 51, a ring gear 53and a planet carrier 55 with planet gears 52. The second rear-mountedplanetary gear set NS2′ of the second rear-mounted group NS′ is designedas a plus-transmission and comprises a sun wheel 61, a ring gear 63 andtwo coupled planet carriers 65′ and 65″ with interior and exteriorplanet gears 62′ and 62″. The sun wheel 51 can be fixed by means of thebrake M′. The ring gears 53 and 63 are connected to each other and canbe connected to the drive shaft 1 (speed n) of the transmission by meansof the clutch H′. The sun wheel 61 is connected to the output of therear-mounted group NS via the output shaft 3 (speed nns). The planetcarriers 55, 65′, 65″ are connected to one another, form the output ofthe second rear-mounted group NS′ and are connected to the output shaft4 (speed nns′) of the transmission.

[0136]FIG. 17D shows exemplary standing gear ratios of this seconddesign of a second rear-mounted group NS′ pursuant to the invention.

[0137] Based on FIGS. 17E and 17F, an exemplary seventeenth design of amulti-step reduction gear pursuant to the invention with a secondrear-mounted group NS′ will now be explained. Overall, this gearcomprises seven shiftable wheel sets and nine switch elements. In thefront-mounted group VS, an additional third, non-shiftable front-mountedplanetary gear set VSA can be arranged in front of the first twofront-mounted planetary gear sets VS1 and VS2, which can be shifted bymeans of the clutches A, B, D, E and the brake C, similar to the designsfourteen and fifteen described above. The rear-mounted group NS, inturn, again comprises a first and a second rear-mounted planetary gearset NS1, NS2 and can be shifted by means of a brake M and a clutch H.Pursuant to the invention, a second, additionally rear-mounted group NS′is arranged behind the rear-mounted group NS, wherein NS′ is connectedfirmly to the output shaft 3 of the rear-mounted group NS rotating atthe output speed nns. The second rear-mounted group NS′ is herebydesigned as a shiftable two-planet carrier/four-shaft transmission andcorresponds to the design shown in FIG. 17A, with third and fourthrear-mounted planetary gear sets NS3 and NS4, as well as a first switchelement M′ designed as a brake and a second switch element H′ designedas a clutch.

[0138] As depicted in FIG. 17E, the drive shaft 1 is connected to thesun wheel 11 a of the third front-mounted planetary gear set VSA.Moreover, the drive shaft 1 can be connected to the planet carrier 25 ofthe planetary gears 22 of the second shiftable front-mounted planetarygear set VS2 via the clutch E, to the ring gear 13 of the firstshiftable front-mounted planetary gear set VS1 by means of the clutch A,to the planet carrier 45 of the planetary gears 42 of the secondrear-mounted planetary gear set NS2 via the clutch H, as well as to aplanet carrier 65 with planet gears 62 of the fourth rear-mountedplanetary gear set NS4 by means of the clutch H′. The thirdfront-mounted planetary gear set VSA is designed as a plus-transmissionin a double-planet design pursuant to the invention. The planet carrier15 a′ with the interior planet gears 12 a′ and the planet carrier 15 a″with the exterior planet gears 12 a″ of the third front-mountedplanetary gear set VSA are connected to each other and are fixed. Thering gear 13 a of the third front-mounted planetary gear set VSA can beconnected to the sun wheel 21 of the second shiftable front-mountedplanetary gear set VS2 by means of the clutch B and to the planetcarrier 25 of the planetary gears 22 of the second shiftablefront-mounted planetary gear set VS2 by means of the clutch D. The sunwheel 21 of the second shiftable front-mounted planetary gear set VS2 isconnected to the sun wheel 11 of the first shiftable front-mountedplanetary gear set VS1 and can be fixed by means of the brake C. Thering gear 13 of the first shiftable front-mounted planetary gear set VS1is connected to the ring gear 23 of the second shiftable front-mountedplanetary gear set VS2. The planet carrier 15 of the planet gears 12 ofthe first shiftable front-mounted planetary gear set VS1 is connected tothe sun wheel 41 of the second rear-mounted planetary gear set NS2 andto the ring gear 33 of the first rear-mounted planetary gear set NS1 bymeans of the spacer shaft 2 rotating at a speed nvs. The planet carrier45 of the planet gears 42 of the second rear-mounted planetary gear setNS2 and the planet carrier 35 of the planet gears 32 of the firstrear-mounted planetary gear set NS1 are connected to each other. The sunwheel 31 of the first rear-mounted planetary gear set NS1 can be fixedby means of the brake M. The ring gear 43 of the second rear-mountedplanetary gear set NS2 is connected to a ring gear 63 of the fourthrear-mounted planetary gear set NS4 by means of the output shaft 3rotating at a speed nns. A sun wheel 51 of the third rear-mountedplanetary gear set NS3 and a sun wheel 61 of the fourth rear-mountedplanetary gear set NS4 are coupled and be fixed by means of the brake M′of the second rear-mounted group NS′. A ring gear 53 of the thirdrear-mounted planetary gear set NS3 and a planet carrier 65 with planetgears 62 of the fourth rear-mounted planetary gear set NS4 are connectedto each other. A planet carrier 55 with planet gears 52 of the thirdrear-mounted planetary gear set NS3 is connected to an output shaft 4 ofthe transmission, which rotates at a speed nns′.

[0139] The aforementioned speed conditions 1 through 7 apply to thespeeds on the shaft and switch elements, as do the following:

[0140] 11. The speeds on the drive shaft 1 and on the shifted switchelement H′ are equal to the input speed n of the drive shaft 1;

[0141] 12. the speed on the shifted switch element M′ is equal to zero;

[0142] 13. the speed on the spider gear, which is connected to theoutput shaft 3, of the second rear-mounted planetary gear set NS2′ ofthe second rear-mounted group NS′, which is generated by shifted switchelements H′ and M′ of the second rear-mounted group NS′, is equalto/greater than the speed nns, which is generated by shifted switchelements in the front-mounted group VS and/or in the rear-mounted groupNS.

[0143]FIG. 17F shows the shift logic of this seventeenth design of aninventive multi-step reduction gear. By selectively shifting the nineswitch elements A, B, C, D, E and H, M as well as H′, M′ a total ofthirty-five forward gears can be shifted with seven wheel sets, withbeneficially close steps and without multiple connection that wouldimpact shifting comfort. A reverse gear is not provided. Similar to thedesigns of the invention pursuant to FIGS. 13 through 16, thisseventeenth design of an inventive multi-step reduction gear is suitableparticularly as a compact multi-gear hub shifting system for bicycles.

[0144] Of course, the second shiftable rear-mounted group NS′ can alsobe combined with other combinations of front-mounted and rear-mountedplanetary gear sets in other further developments of the inventivemulti-step reduction gear, for example, in connection with anon-shiftable front-mounted group and a shiftable rear-mounted group.

[0145] Reference Numerals

[0146] Vs front-mounted group

[0147] VS1 first front-mounted planetary gear set

[0148] VS2 second front-mounted planetary gear set

[0149] VSA third front-mounted planetary gear set

[0150] VSb fourth front-mounted planetary gear set

[0151] NS rear-mounted group

[0152] NS1 first rear-mounted planetary gear set

[0153] NS2 second rear-mounted planetary gear set

[0154] NS′ second rear-mounted group

[0155] NS1′ first rear-mounted planetary gear set of the secondrear-mounted group NS′

[0156] NS2′ second rear-mounted planetary gear set of the secondrear-mounted group NS′

[0157] A, B, C, switch elements of the front-mounted group VS

[0158] D, E

[0159] M, H, L, first through third switch element of the rear-mountedgroup NS

[0160] M′, H′ first and second switch element of the second rear-mounted

[0161] group NS′

[0162] n input speed of the drive shaft

[0163] nva output speed of the VSa wheel set

[0164] nvb output speed of the VSb wheel set

[0165] nvs output speed of the front-mounted group VS

[0166] nns output speed of the rear-mounted group NS

[0167] nns′ output speed of the second rear-mounted group NS′

[0168]1 drive shaft

[0169]2 spacer shaft

[0170]3 output shaft (driven shaft)

[0171]4 output shaft

[0172]11 sun wheel of the VS1 wheel set

[0173]12 planet gear of the VS1 wheel set

[0174]12′ interior planetary gear of the VS1 wheel set

[0175]12″ exterior planetary gear of the VS1 wheel set

[0176]13 ring gear of the VS1 wheel set

[0177]15 planet carrier of the VS1 wheel set

[0178]15′ planet carrier of the interior planetary gears of the VS1wheel set

[0179]15″ planet carrier of the exterior planetary gears of the VS1wheel set

[0180]21 sun wheel of the VS2 wheel set

[0181]22 planet gear of the VS2 wheel set

[0182]22′ interior planetary gear of the VS2 wheel set

[0183]22″ exterior planetary gear of the VS2 wheel set

[0184]23 ring gear of the VS2 wheel set

[0185]25 planet carrier of the VS2 wheel set

[0186]25′ planet carrier of the interior planetary gears of the VS2wheel set

[0187]25″ planet carrier of the exterior planetary gears of the VS2wheel set

[0188]11 a sun wheel of the VSa wheel set

[0189]12 a planet gear of the VSa wheel set

[0190]12 ak small planet gear of the VSa wheel set

[0191]12 ag large planet gear of the VSa wheel set

[0192]12 a′ interior planetary gear of the VSa wheel set

[0193]12 a″ exterior planetary gear of the VSa wheel set

[0194]13 a ring gear of the VSa wheel set

[0195]15 a planet carrier of the VSa wheel set

[0196]15 a′ planet carrier of the interior planetary gears of the VSawheel set

[0197]15 a″ planet carrier of the exterior planetary gears of the VSawheel set

[0198]11 b sun wheel of the VSb wheel set

[0199]12 b′ interior planetary gear of the VSb wheel set

[0200]12 b″ exterior planetary gear of the VSb wheel set

[0201]13 b ring gear of the VSb wheel set

[0202]15 b′ planet carrier of the interior planetary gears of the VSbwheel set

[0203]15 b″ planet carrier of the exterior planetary gears of the VSbwheel set

[0204]31 sun wheel of the NS1 wheel set

[0205]32 planet gear of the NS1 wheel set

[0206]32′ interior planetary gear of the NS1 wheel set

[0207]32″ exterior planetary gear of the NS1 wheel set

[0208]33 ring gear of the NS1 wheel set

[0209]35 planet carrier of the NS1 wheel set

[0210]35′ planet carrier of the interior planetary gears of the NS1wheel set

[0211]35″ planet carrier of the exterior planetary gears of the NS1wheel set

[0212]41 sun wheel of the NS2 wheel set

[0213]42 planet gear of the NS2 wheel set

[0214]42′ interior planetary gear of the NS2 wheel set

[0215]42″ exterior planetary gear of the NS2 wheel set

[0216]43 ring gear of the NS2 wheel set

[0217]45 planet carrier of the NS2 wheel set

[0218]45′ planet carrier of the interior planetary gears of the NS2wheel set

[0219]45″ planet carrier of the exterior planetary gears of the NS2wheel set

[0220]51 sun wheel of the NS1′ wheel set

[0221]52 planet gear of the NS1′ wheel set

[0222]53 ring gear of the NS1′ wheel set

[0223]55 planet carrier of the NS1′ wheel set

[0224]61 sun wheel of the NS2′ wheel set

[0225]62 planet gear of the NS2′ wheel set

[0226]62′ interior planetary gear of the NS2′ wheel set

[0227]62″ exterior planetary gear of the NS2′ wheel set

[0228]63 ring gear of the NS2′ wheel set

[0229]65 planet carrier of the NS2′ wheel set

[0230]65′ planet carrier of the interior planetary gears of the NS2′wheel set

[0231]65″ planet carrier of the exterior planetary gears of the NS2′wheel set

1. Multi-step reduction gear, comprising a drive shaft (1), which isconnected to a front-mounted gear group (VS), an output shaft (3), whichis connected to a rear-mounted gear group (NS), switch elements (A, B,C, D, E) acting on the front-mounted gear group (VS) and switch elements(M, H, L) acting on the rear-mounted gear group (NS), wherein byselectively switching said switch elements (A, B, C, D, E and M, H, L)an input speed (n) of the drive shaft (1) can be transmitted to theoutput shaft (3) for the purpose of shifting at least seven forwardgears in such a way that in order to change from one gear to the nexthighest or next lowest gear the switch elements that have just beenactuated only disconnect one switch element and connect one furtherswitch element, characterized in that the front-mounted gear group (VS)is formed by two coupled, shiftable front-mounted planetary gear sets(VS1, VS2) and a maximum of two further non-shiftable front-mountedplanetary gear sets (VSa, VSb), that the rear-mounted gear group (NS) isfirmly connected to the front-mounted gear group (VS) by means of aspacer shaft (2) rotating at an output speed (nvs) of the front-mountedgear group (VS) and can be connected to the drive shaft (1) by means ofat least one second switch element (H) acting on the rear-mounted geargroup (NS), wherein the output speed (nvs) of the front-mounted geargroup (VS) is generated by selectively closing a maximum of two switchelements (A, B, C, D, E) acting on the front-mounted gear group (VS). 2.Multi-step reduction gear pursuant to claim 1, characterized in that therear-mounted group (NS) is designed as a shiftable two-planetcarrier/four-shaft transmission, comprising a first and a secondrear-mounted planetary gear set (NS1, NS2), a first switch element (M)of the rear-mounted group (NS) designed as a brake and a second switchelement (H) of the rear-mounted group (NS) designed as a clutch, whereinthe rear-mounted group (NS) can be connected to the drive shaft (1)through the second switch element (H), and that at least nine forwardgears can be created.
 3. Multi-step reduction gear pursuant to claim 1,characterized in that the rear-mounted group (NS) is designed as ashiftable two-planet carrier/four-shaft transmission, comprising a firstand a second rear-mounted planetary gear set (NS1, NS2), a first switchelement (M) designed as a clutch, a second switch element (H) designedas a clutch, and a third switch element (L) designed as a clutch or abrake, wherein the rear-mounted group (NS) can be connected to the driveshaft (1) through the second switch element (H), and that at least nineforward gears can be created.
 4. Multi-step reduction gear pursuant toclaims 1, 2 or 3, characterized in that the spacer shaft (2) between thefront-mounted group (VS) and rear-mounted group (NS) is connected to aspider gear of the second rear-mounted planetary gear set (NS2). 5.Multi-step reduction gear pursuant to claim 4, characterized in that thespider gear of the second rear-mounted planetary gear set (NS2), withsaid gear being connected to the spacer shaft (2), is a sun wheel (41)of the second rear-mounted planetary gear set (NS2).
 6. Multi-stepreduction gear pursuant to claim 4, characterized in that the spidergear of the second rear-mounted planetary gear set (NS2), with said gearbeing connected to the spacer shaft (2), is a ring gear (43) of thesecond rear-mounted planetary gear set (NS2).
 7. Multi-step reductiongear pursuant to claims 2, 4 or 5, characterized by the followingfeatures: the front-mounted group (VS) comprises four switch elements(A, B, C, D), a shiftable first front-mounted planetary gear set (VS1)with a sun wheel (11), a ring gear (13) and a planet carrier (15) withplanetary gears (12), as well as a shiftable second front-mountedplanetary gear set (VS2) with a sun wheel (21), a ring gear (23) and aplanet carrier (25) with planetary gears (22); the shiftable firstrear-mounted planetary gear set (NS1) comprises a sun wheel (31), a ringgear (33) and a planet carrier (35) with planetary gears (32); theshiftable second rear-mounted planetary gear set (NS2) comprises a sunwheel (41), a ring gear (43) and a planet carrier (45) with planetarygears (42); the ring gear (13) of the first front-mounted planetary gearset (VS1) and the planet carrier (25) of the second front-mountedplanetary gear set (VS2) are connected to each other and can be fixed bymeans of the fourth switch element (D) of the front-mounted group (VS);the ring gear (23) of the second front-mounted planetary gear set (VS2)and the planet carrier (15) of the first front-mounted planetary gearset (VS1) are connected to each other and via the spacer shaft (2) alsoto the sun wheel (41) of the second rear-mounted planetary gear set(NS2); the ring gear (33) of the first rear-mounted planetary gear set(NS1) and the planet carrier (45) of the second rear-mounted planetarygear set (NS2) are connected to each other and can be connected to thedrive shaft (1) by means of the second switch element (H) of therear-mounted group (NS); the ring gear (43) of the second rear-mountedplanetary gear set (NS2) and the planet carrier (35) of the firstrear-mounted planetary gear set (NS1) are connected to each other and tothe output shaft (3); the sun wheel (11) of the first front-mountedplanetary gear set (VS1) can be connected to the drive shaft (1) throughthe first switch element (A) of the front-mounted group (VS); the sunwheel (21) of the second front-mounted planetary gear set (VS2) can beconnected to the drive shaft (1) through the second switch element (B)of the front-mounted group (VS) and can be fixed by means of the thirdswitch element (C) of the front-mounted group (VS); and the sun wheel(31) of the first rear-mounted planetary gear set (NS1) can be fixed bymeans of the first switch element (M) of the rear-mounted group (NS)[FIG. 1A].
 8. Multi-step reduction gear pursuant to claims 2, 4 or 6,characterized by the following features: the front-mounted group (VS)comprises four switch elements (A, B, D, E), a shiftable firstfront-mounted planetary gear set (VS1) with a sun wheel (11), a ringgear (13) and a planet carrier (15) with planetary gears (12), as wellas a shiftable second front-mounted planetary gear set (VS2) with a sunwheel (21), a ring gear (23) and a planet carrier (25) with planetarygears (22); the shiftable first rear-mounted planetary gear set (NS1)comprises a sun wheel (31), a ring gear (33) and a planet carrier (35)with planetary gears (32); the shiftable second rear-mounted planetarygear set (NS2) comprises a sun wheel (41), a ring gear (43) and a planetcarrier (45) with planetary gears (42); the ring gear (13) of the firstfront-mounted planetary gear set (VS1) and the planet carrier (25) ofthe second front-mounted planetary gear set (VS2) are connected to eachother, can be fixed by means of the third switch element (D) of thefront-mounted group (VS) and can be connected to the drive shaft (1)through the fourth switch element (E) of the front-mounted group (VS);the ring gear (23) of the second front-mounted planetary gear set (VS2)and the planet carrier (15) of the first front-mounted planetary gearset (VS1) are connected to each other and via the spacer shaft (2) alsoto the ring gear (43) of the second rear-mounted planetary gear set(NS2); the ring gear (33) of the first rear-mounted planetary gear set(NS1) and the planet carrier (45) of the second rear-mounted planetarygear set (NS2) are connected to each other and can be connected to thedrive shaft (1) by means of the second switch element (H) of therear-mounted group (NS); the sun wheels (31, 41) of the first and secondrear-mounted planetary gear sets (NS1, NS2) are connected to each otherand can be fixed by means of the first switch element (M) of therear-mounted group (NS); the sun wheel (21) of the second front-mountedplanetary gear set (VS2) can be connected to the drive shaft (1) throughthe second switch element (B) of the front-mounted group (VS); the sunwheel (11) of the first front-mounted planetary gear set (VS1) can befixed by means of the first switch element (A) of the front-mountedgroup (VS); the planet carrier (35) of the first rear-mounted planetarygear set (NS1) is connected to the output shaft (3) [FIG. 2A]. 9.Multi-step reduction gear pursuant to claims 2, 4 or 5, characterized bythe following features: the front-mounted group (VS) comprises fourswitch elements (A, B, C, D), a shiftable first front-mounted planetarygear set (VS1) with a sun wheel (11), a ring gear (13) and two coupledplanet carriers (15′, 15″) with interior and exterior planetary gears(12′, 12″), as well as a shiftable second front-mounted planetary gearset (VS2) with a sun wheel (21), a ring gear (23) and a planet carrier(25) with planetary gears (22); the shiftable first rear-mountedplanetary gear set (NS1) comprises a sun wheel (31), a ring gear (33)and a planet carrier (35) with planetary gears (32); the shiftablesecond rear-mounted planetary gear set (NS2) comprises a sun wheel (41),a ring gear (43) and two coupled planet carriers (45′, 45″) withinterior and exterior planetary gears (42′, 42″); the ring gears (13,23) of the two front-mounted planetary gear sets (VS1, VS2) areconnected to each other and are connected to the sun wheel (41) of thesecond rear-mounted planetary gear set (NS2) by means of the spacershaft (2); the planet carriers (15′, 15″, 25) of the two front-mountedplanetary gear sets (VS1, VS2) are connected to each other and can befixed with the fourth switch element (D) of the front-mounted group(VS); the ring gears (33, 43) of the two rear-mounted planetary gearsets (NS1, NS2) are connected to each other and can be connected to thedrive shaft (1) by means of the second switch element (H) of therear-mounted group (NS); the planet carriers (35, 45″, 45′) of the tworear-mounted planetary gear sets (NS1, NS2) are connected to each otherand to the output shaft (3); the sun wheel (11) of the firstfront-mounted planetary gear set (VS1) can be connected to the driveshaft (1) through the first switch element (A) of the front-mountedgroup (VS); the sun wheel (21) of the second front-mounted planetarygear set (VS2) can be connected to the drive shaft (1) through thesecond switch element (B) of the front-mounted group (VS) and can befixed by means of the third switch element (C) of the front-mountedgroup (VS); and the sun wheel (31) of the first rear-mounted planetarygear set (NS1) can be fixed by means of the first switch element (M) ofthe rear-mounted group (NS) [FIG. 3A].
 10. Multi-step reduction gearpursuant to claims 2, 4 or 5, characterized by the following features:the front-mounted group (VS) comprises five switch elements (A, B, C, D,E), a shiftable first front-mounted planetary gear set (VS1) with a sunwheel (11), a ring gear (13) and a planet carrier (15) with planetarygears (12), as well as a shiftable second front-mounted planetary gearset (VS2) with a sun wheel (21), a ring gear (23) and a planet carrier(25) with planetary gears (22); the shiftable first rear-mountedplanetary gear set (NS1) comprises a sun wheel (31), a ring gear (33)and a planet carrier (35) with planetary gears (32); the shiftablesecond rear-mounted planetary gear set (NS2) comprises a sun wheel (41),a ring gear (43) and a planet carrier (45) with planetary gears (42);the ring gear (13) of the first front-mounted planetary gear set (VS1)and the planet carrier (25) of the second front-mounted planetary gearset (VS2) are connected to each other, can be fixed by means of thefourth switch element (D) of the front-mounted group (VS) and can beconnected to the drive shaft (1) by means of the fifth switch element(E) of the front-mounted group (VS); the ring gear (23) of the secondfront-mounted planetary gear set (VS2) and the planet carrier (15) ofthe first front-mounted planetary gear set (VS1) are connected to eachother and via the spacer shaft (2) also to the sun wheel (41) of thesecond rear-mounted planetary gear set (NS2); the ring gear (33) of thefirst rear-mounted planetary gear set (NS1) and the planet carrier (45)of the second rear-mounted planetary gear set (NS2) are connected toeach other and can be connected to the drive shaft (1) by means of thesecond switch element (H) of the rear-mounted group (NS); the ring gear(43) of the second rear-mounted planetary gear set (NS2) and the planetcarrier (35) of the first rear-mounted planetary gear set (NS1) areconnected to each other and to the output shaft (3); the sun wheel (11)of the first front-mounted planetary gear set (VS1) can be fixed throughthe first switch element (A) of the front-mounted group (VS); the sunwheel (21) of the second front-mounted planetary gear set (VS2) can beconnected to the drive shaft (1) through the second switch element (B)of the front-mounted group (VS) and can be fixed by means of the thirdswitch element (C) of the front-mounted group (VS); and the sun wheel(31) of the first rear-mounted planetary gear set (NS1) can be fixed bymeans of the first switch element (M) of the rear-mounted group (NS)[FIG. 4A].
 11. Multi-step reduction gear pursuant to claims 2, 4 or 6,characterized by the following features: the front-mounted group (VS)comprises five switch elements (A, B, C, D, E), a shiftable firstfront-mounted planetary gear set (VS1) with a sun wheel (11), a ringgear (13) and a planet carrier (15) with planetary gears (12), as wellas a shiftable second front-mounted planetary gear set (VS2) with a sunwheel (21), a ring gear (23) and a planet carrier (25) with planetarygears (22); the shiftable first rear-mounted planetary gear set (NS1)comprises a sun wheel (31), a ring gear (33) and a planet carrier (35)with planetary gears (32); the shiftable second rear-mounted planetarygear set (NS2) comprises a sun wheel (41), a ring gear (43) and a planetcarrier (45) with planetary gears (42); the ring gear (13) of the firstfront-mounted planetary gear set (VS1) and the planet carrier (25) ofthe second front-mounted planetary gear set (VS2) are connected to eachother, can be fixed by means of the fourth switch element (D) of thefront-mounted group (VS) and can be connected to the drive shaft (1) bymeans of the fifth switch element (E) of the front-mounted group (VS);the ring gear (23) of the second front-mounted planetary gear set (VS2)and the planet carrier (15) of the first front-mounted planetary gearset (VS1) are connected to each other and via the spacer shaft (2) alsoto the ring gear (43) of the second rear-mounted planetary gear set(NS2); the ring gear (33) of the first rear-mounted planetary gear set(NS1) and the planet carrier (45) of the second rear-mounted planetarygear set (NS2) are connected to each other and can be connected to thedrive shaft (1) by means of the second switch element (H) of therear-mounted group (NS); the planet carrier (35) of the firstrear-mounted planetary gear set (NS1) is connected to the output shaft(3); the sun wheel (11) of the first front-mounted planetary gear set(VS1) can be connected to the drive shaft (1) through the first switchelement (A) of the front-mounted group (VS); the sun wheel (21) of thesecond front-mounted planetary gear set (VS2) can be connected to thedrive shaft (1) through the second switch element (B) of thefront-mounted group (VS) and can be fixed by means of the third switchelement (C) of the front-mounted group; and the sun wheels (31, 41) ofthe two rear-mounted planetary gear sets (NS1, NS2) are connected toeach other and can be fixed by means of the first switch element (M) ofthe rear-mounted group (NS) [FIG. 5A].
 12. Multi-step reduction gearpursuant to claims 2, 4 or 5, characterized by the following features:the front-mounted group (VS) comprises five switch elements (A, B, C, D,E), a shiftable first front-mounted planetary gear set (VS1) with a sunwheel (11), a ring gear (13) and a planet carrier (15) with planetarygears (12), a shiftable second front-mounted planetary gear set (VS2)with a sun wheel (21), a ring gear (23) and a planet carrier (25) withplanetary gears (22), as well as a non-shiftable third front-mountedplanetary gear set (VSa) with a sun wheel (11 a), a ring gear (13 a) andtwo coupled planet carriers (15 a′, 15 a″) with interior and exteriorplanetary gears (12 a′, 12 a″); the shiftable first rear-mountedplanetary gear set (NS1) comprises a sun wheel (31), a ring gear (33)and a planet carrier (35) with planetary gears (32); the shiftablesecond rear-mounted planetary gear set (NS2) comprises a sun wheel (41),a ring gear (43) and a planet carrier (45) with planetary gears (42);the sun wheel (11 a) of the third front-mounted planetary gear set (VSA)is fixed; the coupled planet carriers (15 a′, 15 a″) of the thirdfront-mounted planetary gear set (VSA) are connected to the drive shaft(1); the sun wheel (11) of the first front-mounted planetary gear set(VS1) can be connected to the drive shaft (1) through the first switchelement (A) of the front-mounted group (VS); the sun wheel (21) of thesecond front-mounted planetary gear set (VS2) can be connected to thering gear (13 a) of the third front-mounted planetary gear set (VSA)through the second switch element (B) of the front-mounted group (VS)and can be fixed through the third switch element (C) of thefront-mounted group (VS); the sun wheel (31) of the first rear-mountedplanetary gear set (NS1) can be fixed through the first switch element(M) of the rear-mounted group (NS); the ring gear (13) firstfront-mounted planetary gear set (VS1) and the planet carrier (25) ofthe second front-mounted planetary gear set (VS2) are connected to eachother, can be fixed through the fourth switch element (D) of thefront-mounted group (VS) and can be connected to the drive shaft (1) bymeans of the fifth switch element (E) of the front-mounted group (VS);the ring gear (23) of the second front-mounted planetary gear set (VS2)and the planet carrier (15) of the first front-mounted group (VS1) areconnected to each other and via the spacer shaft (2) to the sun wheel(41) of the second rear-mounted planetary gear set (NS2); the ring gear(33) of the first rear-mounted planetary gear set (NS1) and the planetcarrier (45) of the second rear-mounted group (NS2) are connected toeach other and can be connected via the second switch element (H) of therear-mounted group (NS) to the drive shaft (1); and the ring gear (43)of the second rear-mounted planetary gear set (NS2) and the planetcarrier (35) of the first rear-mounted group (NS1) are connected to eachother and to the output shaft (3) [FIG. 6A].
 13. Multi-step reductiongear pursuant to claims 2, 4 or 5, characterized by the followingfeatures: the front-mounted group (VS) comprises five switch elements(A, B, C, D, E), a shiftable first front-mounted planetary gear set(VS1) with a sun wheel (11), a ring gear (13) and a planet carrier (15)with planetary gears (12), a shiftable second front-mounted planetarygear set (VS2) with a sun wheel (21), a ring gear (23) and a planetcarrier (25) with planetary gears (22), as well as a non-shiftable thirdfront-mounted planetary gear set (VSa) with a sun wheel (11 a), a ringgear (13 a) and a planet carrier (15 a) with a stepped planetary gearsystem comprising small and large planetary gears (12 ak, 12 ag); theshiftable first rear-mounted planetary gear set (NS1) comprises a sunwheel (31), a ring gear (33) and a planet carrier (35) with planetarygears (32); the shiftable second rear-mounted planetary gear set (NS2)comprises a sun wheel (41), a ring gear (43) and a planet carrier (45)with planetary gears (42); the sun wheel (11 a) of the thirdfront-mounted planetary gear set (VSA) combs with the small planetarygears (12 ak) of the third front-mounted planetary gear set (VSa) and isfixed; the ring gear (13 a) of the third front-mounted planetary gearset (VSA) is connected to the drive shaft (1) and combs on the largeplanetary gears (12 ag) of the third front-mounted planetary gear set(VSA); the sun wheels (11, 21) of the two front-mounted planetary gearsets (VS1, VS2) are connected to each other, can be fixed through thethird switch element (C) of the front-mounted group (VS), and can beconnected to the planet carrier (15 a) of the third front-mountedplanetary gear set (VSa) by means of the second switch element (B) ofthe front-mounted group (VS); the ring gears (13, 23) of the twofront-mounted planetary gear sets (VS1, VS2) are connected to each otherand can be connected to the drive shaft (1) by means of the first switchelement (A) of the front-mounted group (VS); the planet carrier (25) ofthe second front-mounted planetary gear set (VS2) can be connected tothe planet carrier (15 a) of the third front-mounted planetary gear set(VSa) through the fourth switch element (D) of the front-mounted group(VS) as well as to the drive shaft (1) by means of the fifth switchelement (E) of the front-mounted group (VS); the planet carriers (35,45) of the two rear-mounted planetary gear sets (NS1, NS2) are connectedto each other and can be connected to the drive shaft (1) through thesecond switch element (H) of the rear-mounted group (NS); the sun wheel(41) of the second rear-mounted planetary gear set (NS2) and the ringgear (33) of the first rear-mounted group (NS1) are connected to eachother and via the spacer shaft (2) to the planet carrier (15) of thefirst front-mounted planetary gear set (VS1); the sun wheel (31) of thefirst rear-mounted planetary gear set (NS1) can be fixed via the firstswitch element (M) of the rear-mounted group (NS); and the ring gear(43) of the second rear-mounted planetary gear set (NS2) is connected tothe output shaft (3) [FIG. 13A].
 14. Multi-step reduction gear pursuantto claims 2, 4 or 5, characterized by the following features: thefront-mounted group (VS) comprises five switch elements (A, B, C, D, E),a shiftable first front-mounted planetary gear set (VS1) with a sunwheel (11), a ring gear (13) and a planet carrier (15) with planetarygears (12), a shiftable second front-mounted planetary gear set (VS2)with a sun wheel (21), a ring gear (23) and a planet carrier (25) withplanetary gears (22), as well as a non-shiftable third front-mountedplanetary gear set (VSa) with a sun wheel (11 a), a ring gear (13 a) andtwo coupled planet carriers (15 a′, 15 a″) with interior and exteriorplanetary gears (12 a′, 12 a″); the shiftable first rear-mountedplanetary gear set (NS1) comprises a sun wheel (31), a ring gear (33)and a planet carrier (35) with planetary gears (32); the shiftablesecond rear-mounted planetary gear set (NS2) comprises a sun wheel (41),a ring gear (43) and a planet carrier (45) with planetary gears (42);the sun wheel (11 a) of the third front-mounted planetary gear set (VSA)is fixed; the coupled planet carriers (15 a′, 15 a″) of the thirdfront-mounted planetary gear set (VSA) are connected to the drive shaft(1); the sun wheel (11) of the first front-mounted planetary gear set(VS) and the ring gear (23) of the second front-mounted planetary gearset (VS2) are connected to each other and can be connected by means ofthe first switch element (A) of the front-mounted group (VS); the sunwheel (21) of the second front-mounted planetary gear set (VS2) can beconnected to the ring gear (13 a) of the third front-mounted planetarygear set (VSA) through the second switch element (B) of thefront-mounted group (VS) and can be fixed by means of the third switchelement (C) of the front-mounted group (VS); the ring gear (13) of thefirst front-mounted planetary gear set (VS1) and the planet carrier (25)of the second front-mounted planetary gear set (VS2) are connected toeach other, can be connected to the ring gear (13 a) of the thirdfront-mounted planetary gear set (VSA) through the fourth switch element(D) of the front-mounted group (VS) as well as to the drive shaft (1) bymeans of the fifth switch element (E) of the front-mounted group (VS);the sun wheel (41) of the second rear-mounted planetary gear set (NS2)and the ring gear (33) of the first rear-mounted planetary gear set(NS1) are connected to each other and can be connected to the planetcarrier (15) of the first front-mounted planetary gear set (VS1) throughthe spacer shaft (2); the planet carriers (35, 45) of the tworear-mounted planetary gear sets (NS1, NS2) are connected to each otherand can be connected to the drive shaft (1) via the second switchelement (H) of the rear-mounted group (NS); the sun wheel (31) of thefirst rear-mounted planetary gear set (NS1) can be fixed via the firstswitch element (M) of the rear-mounted group (NS); and the ring gear(43) of the second rear-mounted planetary gear set (NS2) is connected tothe output shaft (3) [FIG. 14A].
 15. Multi-step reduction gear pursuantto claims 3, 4 or 5, characterized by the following features: thefront-mounted group (VS) comprises three switch elements (A, B, D), ashiftable first front-mounted planetary gear set (VS1) with a sun wheel(11), a ring gear (13) and a planet carrier (15) with planetary gears(12), as well as a shiftable second front-mounted planetary gear set(VS2) with a sun wheel (21), a ring gear (23) and a planet carrier (25)with planetary gears (22); the shiftable first rear-mounted planetarygear set (NS1) comprises a sun wheel (31), a ring gear (33) and a planetcarrier (35) with planetary gears (32); the shiftable secondrear-mounted planetary gear set (NS2) comprises a sun wheel (41), a ringgear (43) and a planet carrier (45) with planetary gears (42); the sunwheel (11) of the first front-mounted planetary gear set (VS1) can befixed by means of the first switch element (A) of the front-mountedgroup (VS); the sun wheel (21) of the second front-mounted planetarygear set (VS2) can be connected to the drive shaft (1) through thesecond switch element (B) of the front-mounted group (VS); the sun wheel(31) of the first rear-mounted planetary gear set (NS1) can be connectedto the drive shaft (1) by means of the first switch element (M) of therear-mounted group (NS); the ring gear (13) of the first front-mountedplanetary gear set (VS1) and the planet carrier (25) of the secondfront-mounted planetary gear set (VS2) are connected to each other andcan be fixed by means of the third switch element (D) of thefront-mounted group (VS); the ring gear (23) of the second front-mountedplanetary gear set (VS2) and the planet carrier (15) of the firstfront-mounted planetary gear set (VS1) are connected to each other andto the sun wheel (41) of the second rear-mounted group (NS2) via thespacer shaft (2); the ring gear (33) of the first rear-mounted planetarygear set (NS1) and the planet carrier (45) of the second rear-mountedplanetary gear set (NS2) are connected to each other, can be connectedto the drive shaft (1) by means of the second switch element (H) of therear-mounted group (NS) and can be fixed by means of the third switchelement (L) of the rear-mounted group (NS); and the ring gear (43) ofthe second rear-mounted planetary gear set (NS2) and the planet carrier(35) of the first rear-mounted planetary carrier set (NS1) are connectedto each other and to the output shaft (3) [FIG. 7A].
 16. Multi-stepreduction gear pursuant to claims 3, 4 or 5, characterized by thefollowing features: the front-mounted group (VS) comprises three switchelements (A, B, D), a shiftable first front-mounted planetary gear set(VS1) with a sun wheel (11), a ring gear (13) and a planet carrier (15)with planetary gears (12), as well as a shiftable second front-mountedplanetary gear set (VS2) with a sun wheel (21), a ring gear (23) and aplanet carrier (25) with planetary gears (22); the shiftable firstrear-mounted planetary gear set (NS1) comprises a sun wheel (31), a ringgear (33) and a planet carrier (35) with planetary gears (32); theshiftable second rear-mounted planetary gear set (NS2) comprises a sunwheel (41), a ring gear (43) and a planet carrier (45) with planetarygears (42); the sun wheel (11) of the first front-mounted planetary gearset (VS1) can be fixed by means of the first switch element (A) of thefront-mounted group (VS); the sun wheel (21) of the second front-mountedplanetary gear set (VS2) is connected to the drive shaft (1); the sunwheel (31) of the first rear-mounted planetary gear set (NS1) can beconnected to the drive shaft (1) by means of the first switch element(M) of the rear-mounted group (NS); the ring gear (13) of the firstfront-mounted planetary gear set (VS1) and the planet carrier (25) ofthe second front-mounted planetary gear set (VS2) are connected to eachother and can be fixed by means of the third switch element (D) of thefront-mounted group (VS); the ring gear (23) of the second front-mountedplanetary gear set (VS2) and the planet carrier (15) of the firstfront-mounted planetary gear set (VS1) are connected to each other andto the sun wheel (41) of the second rear-mounted group (NS2) via thespacer shaft (2), and can be fixed by means of the second switch element(B) of the front-mounted group (VS); the ring gear (33) of the firstrear-mounted planetary gear set (NS1) and the planet carrier (45) of thesecond rear-mounted planetary gear set (NS2) are connected to eachother, can be connected to the drive shaft (1) by means of the secondswitch element (H) of the rear-mounted group (NS) and can be fixed bymeans of the third switch element (L) of the rear-mounted group (NS);and the ring gear (43) of the second rear-mounted planetary gear set(NS2) and the planet carrier (35) of the first rear-mounted planetarycarrier set (NS1) are connected to each other and to the output shaft(3) [FIG. 7C].
 17. Multi-step reduction gear pursuant to claims 3, 4 or5, characterized by the following features: the front-mounted group (VS)comprises three switch elements (A, B, D), a shiftable firstfront-mounted planetary gear set (VS1) with a sun wheel (11), a ringgear (13) and a planet carrier (15) with planetary gears (12), as wellas a shiftable second front-mounted planetary gear set (VS2) with a sunwheel (21), a ring gear (23) and two coupled planet carriers (25′, 25″)with interior and exterior planetary gears (22′, 22″); the shiftablefirst rear-mounted planetary gear set (NS1) comprises a sun wheel (31),a ring gear (33) and two coupled planet carriers (35′, 35″) withinterior and exterior planetary gears (32′, 32″); the shiftable secondrear-mounted planetary gear set (NS2) comprises a sun wheel (41), a ringgear (43) and a planet carrier (45) with planetary gears (42); the sunwheel (11) of the first front-mounted planetary gear set (VS1) can befixed by means of the first switch element (A) of the front-mountedgroup (VS); the sun wheel (21) of the second front-mounted planetarygear set (VS2) is connected to the drive shaft (1); the ring gears (13,23) of the two front-mounted planetary gear sets (VS1, VS2) areconnected to each other and can be fixed through the third switchelement (D) of the front-mounted group (VS); the planet carriers (15,25′, 25″) of the two front-mounted planetary gear sets (VS1, VS2) areconnected to each other, can be fixed by means of the second switchelement (B) of the front-mounted group (VS), and are connected to thesun wheel (41) of the second rear-mounted planetary gear set (NS2) viathe spacer shaft (2); the sun wheel (31) of the first rear-mountedplanetary gear set (NS1) can be connected to the drive shaft (1) bymeans of the first switch element (M) of the rear-mounted group (NS);the planet carriers (35′, 35″, 45) of the two rear-mounted planetarygear sets (NS1, NS2) connected to each other can be connected to thedrive shaft (1) by means of the second switch element (H) of therear-mounted group (NS) and can be fixed by means of the third switchelement (L) of the rear-mounted group (NS); and the ring gears (33, 43)of the two rear-mounted planetary gear sets (NS1, NS2) are connected toeach other and to the output shaft (3) [FIG. 8A].
 18. Multi-stepreduction gear pursuant to claims 3, 4 or 6, characterized by thefollowing features: the front-mounted group (VS) comprises three switchelements (A, B, D), a shiftable first front-mounted planetary gear set(VS1) with a sun wheel (11), a ring gear (13) and a planet carrier (15)with planetary gears (12), as well as a shiftable second front-mountedplanetary gear set (VS2) with a sun wheel (21), a ring gear (23) and aplanet carrier (25) with planetary gears (22); the shiftable firstrear-mounted planetary gear set (NS1) comprises a sun wheel (31), a ringgear (33) and a planet carrier (35) with planetary gears (32); theshiftable second rear-mounted planetary gear set (NS2) comprises a sunwheel (41), a ring gear (43) and a planet carrier (45) with planetarygears (42); the sun wheels (11, 21) of the two front-mounted planetarygear sets (VS1, VS2) are connected to each other and can be fixed bymeans of the first switch element (A) of the front-mounted group (VS);the ring gear (23) of the second front-mounted planetary gear set (VS2)is connected to the drive shaft (1); the ring gear (13) of the firstfront-mounted planetary gear set (VS1) and the planet carrier (25) ofthe second front-mounted planetary gear set (VS2) are connected to eachother and can be fixed by means of the third switch element (D) of thefront-mounted group (VS); the planet carrier (15) of the firstfront-mounted planetary gear set (VS1) can be fixed by means of thesecond switch element (B) of the front-mounted group and is connected tothe ring gear (43) of the second rear-mounted planetary gear set (NS2)via the spacer shaft (2); the sun wheels (31, 41) of the tworear-mounted planetary gear sets are connected to each other and can beconnected to the drive shaft (1) by means of the first switch element(M) of the rear-mounted group (NS); the ring gear (33) of the firstrear-mounted planetary gear set (NS1) and the planet carrier (45) of thesecond rear-mounted planetary carrier set (NS2) are connected to eachother, can be connected to the drive shaft (1) via the second switchelement (H) of the rear-mounted group (NS) and can be fixed with thethird switch element (L) of the rear-mounted group (NS); the planetcarrier (35) of the first rear-mounted planetary gear set (NS1) isconnected to the output shaft (3) [FIG. 9A].
 19. Multi-step reductiongear pursuant to claims 3, 4 or 5, characterized by the followingfeatures: the front-mounted group (VS) comprises four switch elements(A, B, D, E), a shiftable first front-mounted planetary gear set (VS1)with a sun wheel (11), a ring gear (13) and a planet carrier (15) withplanetary gears (12), as well as a shiftable second front-mountedplanetary gear set (VS2) with a sun wheel (21), a ring gear (23) and aplanet carrier (25) with planetary gears (22); the shiftable firstrear-mounted planetary gear set (NS1) comprises a sun wheel (31), a ringgear (33) and a planet carrier (35) with planetary gears (32); theshiftable second rear-mounted planetary gear set (NS2) comprises a sunwheel (41), a ring gear (43) and a planet carrier (45) with planetarygears (42); the sun wheel (11) of the first front-mounted planetary gearset (VS1) can be fixed by means of the first switch element (A) of thefront-mounted group (VS); the sun wheel (21) of the second front-mountedplanetary gear set (VS2) can be connected to the drive shaft (1) throughthe second switch element (B) of the front-mounted group (VS); the sunwheel (31) of the first rear-mounted planetary gear set (NS1) can beconnected to the drive shaft (1) by means of the first switch element(M) of the rear-mounted group (NS); the ring gear (13) of the firstfront-mounted planetary gear set (VS1) and the planet carrier (25) ofthe second front-mounted planetary gear set (VS2) are connected to eachother, can be fixed by means of the third switch element (D) of thefront-mounted group (VS), and can be connected to the drive shaft (1)through the fourth switch element (E) of the front-mounted group (VS);the ring gear (23) of the second front-mounted planetary gear set (VS2)and the planet carrier (15) of the first front-mounted planetary gearset (VS1) are connected to each other and via the spacer shaft (2) tothe sun wheel (41) of the second rear-mounted group (NS2); the ring gear(33) of the first rear-mounted planetary gear set (NS1) and the planetcarrier (45) of the second rear-mounted planetary gear set (NS2) areconnected to each other, can be connected to the drive shaft (1) bymeans of the second switch element (H) of the rear-mounted group (NS)and can be fixed by means of the third switch element (L) of therear-mounted group (NS); and the ring gear (43) of the secondrear-mounted planetary gear set (NS2) and the planet carrier (35) of thefirst rear-mounted planetary carrier set (NS1) are connected to eachother and to the output shaft (3) [FIG. 10A].
 20. Multi-step reductiongear pursuant to claims 3, 4 or 5, characterized by the followingfeatures: the front-mounted group (VS) comprises four switch elements(A, B, C, D), a shiftable first front-mounted planetary gear set (VS1)with a sun wheel (11), a ring gear (13) and a planet carrier (15) withplanetary gears (12), as well as a shiftable second front-mountedplanetary gear set (VS2) with a sun wheel (21), a ring gear (23) and aplanet carrier (25) with planetary gears (22); the shiftable firstrear-mounted planetary gear set (NS1) comprises a sun wheel (31), a ringgear (33) and a planet carrier (35) with planetary gears (32); theshiftable second rear-mounted planetary gear set (NS2) comprises a sunwheel (41), a ring gear (43) and a planet carrier (45) with planetarygears (42); the sun wheel (11) of the first front-mounted planetary gearset (VS1) can be connected to the drive shaft (1) by means of the firstswitch element (A) of the front-mounted group (VS); the sun wheel (21)of the second front-mounted planetary gear set (VS2) can be connected tothe drive shaft (1) through the second switch element (B) of thefront-mounted group (VS) and can be fixed by means of the third switchelement (C) of the front-mounted group (VS); the ring gear (13) of thefirst front-mounted planetary gear set (VS1) and the planet carrier (25)of the second front-mounted planetary gear set (VS2) are connected toeach other and can be fixed by means of the fourth switch element (D) ofthe front-mounted group (VS); the ring gear (23) of the secondfront-mounted planetary gear set (VS2) and the planet carrier (15) ofthe first front-mounted planetary gear set (VS1) are connected to eachother and to the spacer shaft (2); the spacer shaft (2) is connected tothe sun wheel (41) of the second rear-mounted planetary gear set (NS2)and to the ring gear (33) of the first rear-mounted planetary gear set(NS1) coupled to said sun wheel (41); the sun wheel (31) of the firstrear-mounted planetary gear set (NS1) can be connected to the driveshaft (1) by means of the first switch element (M) of the rear-mountedgroup (NS); the planet carriers (35, 45) of the two rear-mountedplanetary gear sets (NS1, NS2) are connected to each other, can beconnected to the drive shaft (1) via the second switch element (H) ofthe rear-mounted group (NS) and can be fixed by means of the thirdswitch element (L) of the rear-mounted group (NS); the ring gear (43) ofthe second rear-mounted planetary gear set (NS2) is connected to theoutput shaft (3) [FIG. 11A].
 21. Multi-step reduction gear pursuant toclaims 3, 4 or 5, characterized by the following features: thefront-mounted group (VS) comprises five switch elements (A, B, C, D, E),a shiftable first front-mounted planetary gear set (VS1) with a sunwheel (11), a ring gear (13) and a planet carrier (15) with planetarygears (12), a shiftable second front-mounted planetary gear set (VS2)with a sun wheel (21), a ring gear (23) and a planet carrier (25) withplanetary gears (22), as well as a non-shiftable third front-mountedplanetary gear set (VSA) with a sun wheel (11 a), a ring gear (13 a) andtwo coupled planet carriers (15 a′, 15 a″) with interior and exteriorplanetary gears (12 a′, 12 a″); the shiftable first rear-mountedplanetary gear set (NS1) comprises a sun wheel (31), a ring gear (33)and a planet carrier (35) with planetary gears (32); the shiftablesecond rear-mounted planetary gear set (NS2) comprises a sun wheel (41),a ring gear (43) and a planet carrier (45) with planetary gears (42);the drive shaft (1) is connected to the sun wheel (11 a) of the thirdfront-mounted planetary gear set (VSA); the drive shaft (1) can beconnected to the sun wheel (11) of the first front-mounted planetarygear set (VS1) via the first switch element (A) of the front-mountedgroup (VS); the drive shaft (1) can be connected to the planet carrier(25) of the second front-mounted planetary gear set (VS2) via the fifthswitch element (E) of the front-mounted group (VS); the drive shaft (1)can be connected to the planet carrier (45) of the second rear-mountedplanetary gear set (NS2) via the second switch element (H) of therear-mounted group (NS); the coupled planet carriers (15 a′, 15 a″) ofthe third front-mounted planetary gear set (VSA) are fixed; the sunwheel (21) of the second front-mounted planetary gear set (VS2) can befixed by means of the third switch element (C) of the front-mountedgroup (VS), especially by means of the planet carrier (15 a″) of theexterior planetary gears (12 a″) of the third front-mounted planetarygear set (VSA); the ring gear (13 a) of the third front-mountedplanetary gear set (VSA) can be connected to the sun wheel (21) of thesecond front-mounted planetary gear set (VS2) through the second switchelement (B) of the front-mounted group (VS); the ring gear (13 a) of thethird front-mounted planetary gear set (VSA) can be connected to theplanet carrier (25) of the second front-mounted planetary gear set (VS2)through the fourth switch element (D) of the front-mounted group (VS);the ring gear (13 a) of the third front-mounted planetary gear set (VSA)can be connected to the planet carrier (45) of the second rear-mountedplanetary gear set (NS2) through the third switch element (L) of therear-mounted group (NS); the ring gear (13 a) of the third front-mountedplanetary gear set (VSA) can be connected to the sun wheel (31) of thefirst rear-mounted planetary gear set (NS1) by means of the first switchelement (M) of the rear-mounted group (NS); the planet carrier (25) ofthe second front-mounted planetary gear set (VS2) and the ring gear (13)of the first front-mounted planetary gear set (VS1) are connected toeach other; the sun wheel (11) of the first front-mounted planetary gearset (VS1) and the ring gear (23) of the second front-mounted planetarygear set (VS2) are connected to each other; the planet carrier (15) ofthe first front-mounted planetary gear set (VS1) is connected to the sunwheel (41) of the second rear-mounted planetary gear set (NS2) via thespacer shaft (2); the planet carrier (45) of the second rear-mountedplanetary gear set (NS2) is connected to the ring gear (33) of the firstrear-mounted planetary gear set (NS1); and the planet carrier (35) ofthe first rear-mounted planetary gear set (NS1) is connected to the ringgear (43) of the second rear-mounted planetary gear set (NS2) and to theoutput shaft (3) [FIG. 15A].
 22. Multi-step reduction gear pursuant toclaims 3, 4 or 5, characterized by the following features: thefront-mounted group (VS) comprises a shiftable first front-mountedplanetary gear set (VS1), a shiftable second front-mounted planetarygear set (VS2), a non-shiftable third front-mounted planetary gear set(VSA), a non-shiftable fourth front-mounted planetary gear set (VSb) andfive switch elements (A, B, C, D, E); the drive shaft (1) is connectedto the sun wheel (11 b) of the fourth front-mounted planetary gear set(VSb); the drive shaft (1) can be connected to a sun wheel (21) of thesecond shiftable front-mounted planetary gear set (VS2) via the secondswitch element (B) of the front-mounted group (VS); the drive shaft (1)can be connected to a planet carrier (25) comprising planetary gears(22) of the second front-mounted planetary gear set (VS2) via the fifthswitch element (E) of the front-mounted group (VS); the drive shaft (1)can be connected to a planet carrier (45) comprising planetary gears(42) of the second rear-mounted planetary gear set (NS2) via the secondswitch element (H) of the rear-mounted group (NS); a sun wheel (11 a) ofthe third front-mounted planetary gear set (VSA) is fixed; a planetcarrier (15 a) with planetary gears (12 a) of the third front-mountedplanetary gear set (VSA) is connected to a planet carrier (15 b″)comprising exterior planetary gears (12 b″) of the fourth front-mountedplanetary gear set (VSb); the planet carrier (15 a) of the thirdfront-mounted planetary gear set (VSa) is connected to a planet carrier(15 b′) with interior planetary gears (12 b′) of the fourthfront-mounted planetary gear set (VSb); the planet carrier (15 a) of thethird front-mounted planetary gear set (VSA) is connected to the sunwheel (21) of the second shiftable front-mounted planetary gear set(VS2) by means of the third switch element (C) of the front-mountedgroup (VS); the planet carrier (15 a) of the third front-mountedplanetary gear set (VSA) can be connected to the planet carrier (25) ofthe second shiftable front-mounted planetary gear set (VS2) by means ofthe fourth switch element (D) of the front-mounted group (VS); theplanet carrier (15 a) of the third front-mounted planetary gear set(VSA) can be connected to a planet carrier (35″) with exterior planetarygears (32″) of the first rear-mounted planetary gear set (NS1) by meansof the third switch element (L) of the rear-mounted group (NS); theplanetary gears (12 a) of the third front-mounted planetary gear set(VSA) and the exterior planetary gears (12 b″) of the fourthfront-mounted planetary gear set (VSb) are grouped; a ring gear (13 a)of the third front-mounted planetary gear set (VSA) and a ring gear (13b) of the fourth front-mounted planetary gear set (VSb) are connected toeach other; the ring gears (13 a, 13 b) of the third and fourthfront-mounted planetary gear sets (VSa, VSb) can be connected to a sunwheel (11) of the first shiftable front-mounted planetary gear set (VS1)by means of the first switch element (A) of the front-mounted group(VS); the ring gears (13 a, 13 b) of the third and fourth front-mountedplanetary gear sets (VSa, VSb) can be connected to a sun wheel (31) ofthe first rear-mounted planetary gear set (NS1) by means of the firstswitch element (M) of the rear-mounted group (NS); the sun wheel (11) ofthe first shiftable front-mounted planetary gear set (VS1) is connectedto a ring gear (23) of the second shiftable front-mounted planetary gearset (VS2); the planet carrier (25) of the second shiftable front-mountedplanetary gear set (VS2) is connected to the a ring gear (13) of thefirst shiftable front-mounted planetary gear set (VS1); the planetcarrier (15) with planetary gears (12) of the first shiftablefront-mounted planetary gear set (VS1) is connected to a sun wheel (41)of the second rear-mounted planetary gear set (NS2) via the spacer shaft(2); the planet carrier (35″) with the exterior planetary gears (32″) ofthe first rear-mounted planetary gear set (NS1) and a planet carrier(35′) with interior planetary gears (32′) of the first rear-mountedplanetary gear set (NS1) and the planet carrier (45) with the planetarygears (42) of the second rear-mounted planetary gear set (NS2) areconnected to each other; the exterior planetary gears (32″) of the firstrear-mounted planetary gear set (NS1) and the planetary gears (42) ofthe second rear-mounted planetary gear set (NS2) are grouped; a ringgear (33) of the first rear-mounted planetary gear set (NS1) and a ringgear (43) of the second rear-mounted planetary gear set (NS2) areconnected to each other; the ring gears (33, 43) of the first and secondrear-mounted planetary gear sets (NS1, NS2) are connected to the outputshaft (3) [FIG. 16A].
 23. Multi-step reduction gear, comprising a driveshaft (1), which is connected to a front-mounted gear group (VS), anoutput shaft (3), which is connected to a rear-mounted gear group (NS),switch elements (A, B) acting on the front-mounted gear group (VS) andswitch elements (M, H, L) acting on the rear-mounted gear group (NS),wherein by selectively switching said switch elements (A, B, M, H, L) aninput speed (n) of the drive shaft (1) can be transmitted to the outputshaft (3) for the purpose of shifting at least seven forward gears insuch a way that in order to change from one gear to the next highest ornext lowest gear the switch elements that have just been actuated onlydisconnect one switch element and connect one further switch element,and wherein the rear-mounted group (NS) is designed as a shiftabletwo-planet carrier/four-shaft transmission with a first and a secondrear-mounted planetary gear set (NS1, NS2), characterized in that thefront-mounted gear group (VS) is formed by two front-mounted planetarygear sets (VS1, VS2), of which at least one is shiftable, that theshiftable rear-mounted gear group (NS) is firmly connected to thefront-mounted gear group (VS) by means of a spacer shaft (2) rotating atan output speed (nva) of the front-mounted gear group (VS) and can beconnected to the drive shaft (1) by means of at least one switch element(M, H, L) acting on the shiftable rear-mounted gear group (NS), whereinthe output speed (nvs) of the front-mounted gear group (VS) is generatedby selectively closing one of the switch elements (A, B) acting on thefront-mounted gear group (VS) in one of the two front-mounted planetarygear sets (VS1, VS2).
 24. Multi-step reduction gear pursuant to claim23, characterized by the following features: the drive shaft (1) isconnected to a sun wheel (11) of the first, shiftable front-mountedplanetary gear set (VS1); the drive shaft (1) can be connected to a sunwheel (21) of the second, shiftable front-mounted planetary gear set(VS2) via the second switch element (B) of the front-mounted group (VS);a planet carrier (25) with planetary gears (22) of the second shiftablefront-mounted planetary gear set (VS2) is fixed; a ring gear (13) of thefirst shiftable front-mounted planetary gear set (VS1) can be connectedto the fixed planet carrier (25) of the second shiftable front-mountedplanetary gear set (VS2) by means of the first switch element (A) of thefront-mounted group; the drive shaft (1) can be connected to a sun wheel(31) of the first rear-mounted planetary gear set (NS1) by means of thefirst switch element (M) of the rear-mounted group (NS); the drive shaft(1) can be connected to a planet carrier (45) with planetary gears (42)of the second rear-mounted planetary gear set (NS2) by means of thesecond switch element (H) of the rear-mounted group (NS); the planetcarrier (45) of the second rear-mounted planetary gear set (NS2) isconnected to a ring gear (33) of the first rear-mounted planetary gearset (NS1); the planet carrier (45) of the second rear-mounted planetarygear set (NS2) can be fixed by means of the third switch element (L) ofthe rear-mounted group (NS); a ring gear (23) of the second shiftablefront-mounted planetary gear set (VS2) is connected to a planet carrier(15) of the planetary gears (12) of the first front-mounted planetarygear set (VS1); a ring gear (23) of the second shiftable front-mountedplanetary gear set (VS2) is connected to a sun wheel (41) of the secondrear-mounted planetary gear set (NS2) via the spacer shaft (2); a ringgear (43) of the second rear-mounted planetary gear set (NS2) isconnected to a planet carrier (35) of the planetary gears (32) of thefirst rear-mounted planetary gear set (NS1); and the ring gear (43) ofthe second rear-mounted planetary gear set (NS2) is connected to theoutput shaft (3)[FIG. 12A].
 25. Multi-step reduction gear pursuant toone of the previous claims, characterized in that a second rear-mountedgroup (NS′) designed as a shiftable two-planet carrier/four-shafttransmission is arranged after the rear-mounted group (NS) and that atleast eighteen forward gears can be created, wherein the secondrear-mounted group (NS′) is formed by two shiftable rear-mountedplanetary gear sets (NS1′, NS2′), a first switch element (M′) designedas a brake and a second switch element (H′) designed as a clutch, thatit is firmly connected on the input side to the output shaft (3)rotating at the output speed (nns) of the rear-mounted group (NS) andcan be connected to the drive shaft (1) via the second switch element(H′) of the second rear-mounted group (NS′) as well as is connected onthe output side to an output shaft (4) of the multi-step reduction gear.26. Multi-step reduction gear pursuant to claim 25, characterized by thefollowing features: the first rear-mounted planetary gear set (NS1′) ofthe second rear-mounted group (NS′) comprises a sun wheel (51), a ringgear (53) and a planet carrier (55) with planetary gears (52); thesecond rear-mounted planetary gear set (NS2′) of the second rear-mountedgroup (NS′) comprises a sun wheel (61), a ring gear (63) and a planetcarrier (65) with planetary gears (62); the sun wheels (51, 61) of thetwo rear-mounted planetary gear sets (NS1′, NS2′) of the secondrear-mounted group (NS′) are connected to each other and can be fixed bymeans of the first switch element (M′) of the second rear-mounted group(NS′); the ring gear (53) of the first rear-mounted planetary gear set(NS1′) of the second rear-mounted group (NS′) and the planet carrier(65) of the second rear-mounted planetary gear set (NS2′) of the secondrear-mounted group (NS′) are connected to each other and can beconnected to the drive shaft (1) via the second switch element (H′) ofthe second rear-mounted group (NS′); the ring gear (63) of the secondrear-mounted planetary gear set (NS2′) of the second rear-mounted group(NS′) is connected to the output shaft (3); and the planet carrier (55)of the first rear-mounted planetary gear set (NS1′) of the secondrear-mounted group (NS′) is connected to the output shaft (4) FIG. 17A].27. Multi-step reduction gear pursuant to claim 25, characterized by thefollowing features: the first rear-mounted planetary gear set (NS1′) ofthe second rear-mounted group (NS′) comprises a sun wheel (51), a ringgear (53) and a planet carrier (55) with planetary gears (52); thesecond rear-mounted planetary gear set (NS2′) of the second rear-mountedgroup (NS′) comprises a sun wheel (61), a ring gear (63) and two coupledplanet carriers (65′, 65″) with interior and exterior planetary gears(62′, 62″); the sun wheel (51) of the first rear-mounted planetary gearset (NS1′) of the second rear-mounted group (NS′) can be fixed by meansof the first switch element (M′) of the second rear-mounted group (NS′);the ring gears (53, 63) of the two rear-mounted planetary gear sets(NS1′, NS2′) of the second rear-mounted group (NS′) are connected toeach other and can be connected to the drive shaft (1) via the secondswitch element (H′) of the second rear-mounted group (NS′); the sunwheel (61) of the second rear-mounted planetary gear set (NS2′) of thesecond rear-mounted group (NS′) is connected to the output shaft (3);and the planet carriers (55, 65′, 65″) of the two rear-mounted planetarygear sets (NS1′, NS2′) of the second rear-mounted group (NS′) areconnected to each other and to the output shaft (4)[FIG. 17C]. 28.Multi-step reduction gear pursuant to claim 26, characterized by thefollowing features: the drive shaft (1) is connected to a sun wheel (11a) of the third front-mounted planetary gear set (VSa); the drive shaft(1) can be connected to a planet carrier (25) with planetary gears (22)of the second front-mounted planetary gear set (VS2) via the fifthswitch element (E) of the front-mounted group (VS); the drive shaft (1)can be connected to a ring gear (13) of the first front-mountedplanetary gear set (VS1) via the first switch element (A) of thefront-mounted group (VS); the drive shaft (1) can be connected to aplanet carrier (45) with planetary gears (42) of the second rear-mountedplanetary gear set (NS2) via the second switch element (H) of therear-mounted group (NS); the third front-mounted planetary gear set(VSa) is designed as a plus-transmission; a planet carrier (15 a′) withinterior planetary gears (12 a′) of the third front-mounted planetarygear set (VSa) and a planet carrier (15 a″) with exterior planetarygears (12 a″) of the third front-mounted planetary gear set (VSa) areconnected to each other and fixed; a ring gear (13 a) of the thirdfront-mounted planetary gear set (VSa) can be connected to a sun wheel(21) of the second front-mounted planetary gear set (VS2) by means ofthe second switch element (B) of the front-mounted group; the ring gear(13 a) of the third front-mounted planetary gear set (VSA) can beconnected to a planet carrier (25) of the second front-mounted planetarygear set (VS2) by means of the fourth switch element (D) of thefront-mounted group; the sun wheel (21) of the second front-mountedplanetary gear set (VS2) is connected to a sun wheel (11) of the firstfront-mounted planetary gear set (VS1); the sun wheel (21) of the secondfront-mounted planetary gear set (VS2) can be fixed by means of thethird switch element (C) of the front-mounted group (VS); the ring gear(13) of the first front-mounted planetary gear set (VS1) is connected toa ring gear (23) of the second front-mounted planetary gear set (VS2); aplanet carrier (15) with planetary gears (12) of the first front-mountedplanetary gear set (VS1) is connected to a sun wheel (41) of the secondrear-mounted planetary gear set (NS2) via the spacer shaft (2); theplanet carrier (15) of the first front-mounted planetary gear set (VS1)is connected to a ring gear (33) of the first rear-mounted planetarygear set (NS1); the planet carrier (45) of the second rear-mountedplanetary gear set (NS2) and a planet carrier (35) comprising planetarygears (32) of the first rear-mounted planetary gear set (NS1) areconnected to each other; a sun wheel (31) of the first rear-mountedplanetary gear set (NS1) can be fixed by means of the first switchelement (M) of the rear-mounted group (NS); and a ring gear (43) of thesecond rear-mounted planetary gear set (NS2) is connected to the secondrear-mounted group (NS′) via the output shaft (3) [FIG. 17E]. 1-28.(CANCELED)
 29. (NEW) A multi-step reduction gear comprising: a driveshaft (1), which is connected to a front-mounted gear group (VS), anoutput shaft (3), which is connected to a rear-mounted gear group (NS),switch elements (A, B, C, D, E) acting on the front-mounted gear group(VS); and switch elements (M, H, L) acting on the rear-mounted geargroup (NS), wherein by selectively switching said switch elements (A, B,C, D, E and M, H, L) an input speed (n) of the drive shaft (1) can betransmitted to the output shaft (3) for the purpose of shifting at leastseven forward gears in such a way that in order to change from one gearto the next highest or next lowest gear the switch elements that havejust been actuated only disconnect one switch element and connect onefurther switch element, wherein the rear-mounted group (NS) can beconnected to the drive shaft (1) via at least one second switch element(H) acting on the rear-mounted group (NS), characterized in that thefront-mounted gear group (VS) is formed by two coupled, shiftablefront-mounted planetary gear sets (VS1, VS2) and a maximum of twofurther non-shiftable front-mounted planetary gear sets (VSa, VSb), andthat the rear-mounted gear group (NS) is firmly connected to thefront-mounted gear group (VS) exactly by means of one spacer shaft (2)rotating at an output speed (nvs) of the front-mounted gear group (VS),with said shaft not being connected to a switch element, wherein theoutput speed (nvs) of the front-mounted gear group (VS) is generated byselectively closing a maximum of two switch elements (A, B, C, D, E)acting on the front-mounted gear group (VS).
 30. (NEW) The multi-stepreduction gear pursuant to claim 29, wherein the rear-mounted group (NS)is a shiftable two-planet carrier/four-shaft transmission, including afirst and a second rear-mounted planetary gear set (NS1, NS), a firstswitch element (M) of the rear-mounted group (NS) is a brake and asecond switch element (H) of the rear-mounted group (NS) is a clutch,wherein the rear-mounted group (NS) can be connected to the drive shaft(1) through the second switch element (H), and that at least nineforward gears can be created.